Motor Oil University Confused Me

[Mike2914]

Hey all,

A friend referred me to this site and I read through the "Motor Oil University" series but got confused along the way. Hopefully yall will be able to clear up my misunderstandings and help me figure out the right oil to use at the same time.

First, I understand the oil articles said they were general / vague and maybe that's where my confusion comes in. I'm assuming my biggest sticking point is the statement that all engines want to be at a viscosity of 10 at 212F. Further, it states that all oils are too thick when cold. Based on these two statements, wouldn't it make sense that everyone would want the oil with the lowest viscosity possible at room temp (cold) while still achieving a viscosity of 10 at 212F? If I read the articles right, that means you would always want a 0W - oil. The article (at least to me) didn't really cover why someone would use a 0W-20 vs 0W-30 vs 0W-40. I can only interpret that the 0W-20 has a lower viscosity at 212F than 0W-40..but why would you use either if a -30 has viscosity of 10 at 212F which is what you want?

The articles were clear in saying the different viscosity points at different temperatures for different oil types. Is this data gathered empirically or do manufacturers make it available? I have yet to see any of this data on the label or on the manufacturer websites..probably because then they'd all be on the same playing field.

On to hopefully the easy stuff...

I own a 1997 Jeep Grand Cherokee Laredo 6cyl 2WD and a 2008 Honda CRV 4cyl 2WD. I don't drive rough - just trying to get from point A to point B. Cars are used for a good combination of city/highway driving. My typical commute 1-way involves about 2.5 miles city streets, followed by 8-10 miles of highway, and then 2.5 miles of city streets. I live in FL where it's normally above 70F year-round.

The CRV manual says to use 5W-20 while the Jeep says to use 5W-30. I plan to use synthetic oil just because it seems to be better than mineral oil. I was looking at buying some Mobil1 oil from Walmart and using a Purolator filter. My only question is which "weight" oil to buy. I'm thinking 0W-20 for the CRV and 0W-30 for the Jeep...although I'm still not clear why one uses a 20 and the other uses a 30...

Thanks for helping educate a shade tree mechanic like me!

Mike

 

[DrDusty86]

the 4.0 in the jeep likes a thick 30 weight, just the way it was designed. your CRv has tighter machining and CAFE to thank for the 20 weight. Yes, I would use German Castrol GC 0w30 in the jeep for 5k intervals for the first 3 changes and extend from there. Checking the oil often
The CRv I would use M1 0w20 and go by the oil monitor. Check the oil often

 

[Clevy]

In both your vehicles a syn isn't required and if you are going to follow the oil life monitor(if equipped)or are just going to go with 5000 mile intervals there isn't any need to pay extra for a synthetic.
Where syns really shine are under extreme driving conditions,sustained high rpm driving or extreme cold start up temps,or extended drain intervals.
I only use synthetics in our extreme cold winter temps(-40) otherwise I run conventionals. A vehicle running a 5000 mile drain interval,the oil will look pretty much the same as far as used oil analysis goes whether a syn or mineral oil was used. So yes synthetics are a better product but for almost all of us we don't need them,and a mineral oil will perform more than well enough for most of us,leading to many hundreds of thousands of trouble free miles.
The whole peace of mind stuff is just nonsense really. Now if you've got some kind of performance engine that's boosted for example well in that particular application you may need something special however most of us don't need anything more than that API donut,and can get that oil cheap and without issue.
I use whatever Walmart has on sale that week,and usually buy lots so I don't need to wait for any real sale.

 

[Kuato]

Mike2914,

to BITOG. It's all very confusing to start and hopefully this will help out:


In FL's temps you probably don't need to worry about using a 0w20/30 oil, as a 5w should be the same thickness at start up. But if you wanted to go with 0w30 it certainly wouldn't hurt, and 0w30 is generally a better oil than 5w30.

M1 is a great oil; but for your Jeep, I can say that M1 has historically shown higher amounts of Fe(Iron) in samples, up to 4x the level of what other oils tested. Some will pooh pooh that statement, but the results have shown over and over that the 4.0 doesn't like M1.

With your style of driving, if you aren't planning to extend your oil changes beyond 5000 miles, I agree with Clevy that you could use any conventional ("dino") oil without worry. I used VWB (Valvoline White Bottle) for years in my 4.0s before I switched to synthetic, with great results from UOAs. With some testing, you might be able to go beyond 5000 miles between oil changes. My 4.0 went 5k on VWB, and the test results showed it could have gone further. Some folks on here go 10k on dino oil with good results, but IIRC they extended their intervals gradually to make sure the oil was ok at that distance.

If you wanted to try to go beyond 5000 or maybe 7500, then synthetic is the way to go. Again the 5w30 for the Jeep is available in many many brands, all of which would work great. You could even try the Rotella T6 5w40 available at WM; it is a very good oil and has gotten good results in the 4.0 by those that have tried it (I have not).

Purolator is a very good filter, but they do not warrant it beyond manufacturer's recommended distance. Again to go beyond maybe 7500 miles you'll want a filter designed for longer distances, such as M1 Extended or Amsoil.

Don't know if your Toyota is spec'd for 0w20 or 5w20 oil, but the same concepts as above apply(except the M1, which should be fine for this engine).

 

[chubbs1]

As Clevy said there really is no need for 99.9% of us regular drivers to use "synthetic" oil. Keep it really simple since there are so many options (first off just following 20grade for the CRV and 30grade for the Jeep is the best rule, any API certified oil is fine)

Option 1 conventional: MobilSuper 5k 5w20/5w30
Option 2 "syn": M1 0w20/0w30

If you pick either you will ride forever. This is just a couple of simple choices you can make that won't be wrong and keep your engines in tip top shape.
Let me make it clear though, any major brand will serve you practically the same.

PS: I personally would run 0w20 all year in the CRV until the OLM light comes on. I would run MS5K in the Jeep at 5k/6mo intervals. MS5k has been showing to be absolutely outstanding in the conventional category.

 

[Clevy]

Originally Posted By: chubbs1
As Clevy said there really is no need for 99.9% of us regular drivers to use "synthetic" oil. Keep it really simple since there are so many options (first off just following 20grade for the CRV and 30grade for the Jeep is the best rule, any API certified oil is fine)

Option 1 conventional: MobilSuper 5k 5w20/5w30
Option 2 "syn": M1 0w20/0w30

If you pick either you will ride forever. This is just a couple of simple choices you can make that won't be wrong and keep your engines in tip top shape.
Let me make it clear though, any major brand will serve you practically the same.

PS: I personally would run 0w20 all year in the CRV until the OLM light comes on. I would run MS5K in the Jeep at 5k/6mo intervals. MS5k has been showing to be absolutely outstanding in the conventional category.


I'm a Mobil hater,so I wouldn't personally recommend it however what Chubb is saying is correct.
And I think M1 has a 10000 mile guarantee on the M1 line of oils,and tig is proving in the real world that that particular oci will work fine as well as maintain engine cleanliness.
Personally I'd lean towards sopus although no guarantee,but actually trying to cash in on that kind of warranty would likely require a team of lawyers and more paperwork then a rainforest could produce.
Decide what kind of mileage you want to go between oil changes,then find an oil that fits. I doubt you would have a hard time finding a suitable product that will meet your needs,as most manufacturers produce various grades in varying quality.
If I was leaning towards the longest drain possible Amsoil would by my first choice. They are the longest drain capable oil on the market,from what I've seen,so I'd start there.

 

[Errtt]

Wait!.... night after night, hour after hour you spend in BITOG, the more confusing it gets. Then you have to re-read things over and over just to clarify some things, but then a week later forget details. Then back to square-1, and after doing this repeatedly hope to pick up at least a little something (good and/or bad). I think I'm past time (don't remember) to re-read Motor Oil University myself, again.

Good stuff

 

[CATERHAM]

Originally Posted By: Mike2914

First, I understand the oil articles said they were general / vague and maybe that's where my confusion comes in. I'm assuming my biggest sticking point is the statement that all engines want to be at a viscosity of 10 at 212F. Further, it states that all oils are too thick when cold. Based on these two statements, wouldn't it make sense that everyone would want the oil with the lowest viscosity possible at room temp (cold) while still achieving a viscosity of 10 at 212F? 'd all be on the same playing field.


First welcome to BITOG!

Yes Ali Haas who wrote that piece is basically correct, all oil is too think even at 100C and finding a oil that is as light as possible at room temp's while maintaining an adequate viscosity at normal operating temp's is the ideal scenario.

In a Florida climate the viscosity specification that determines how light an oil will be relative to is it's hot normal operating viscosity is called an oil's viscosity index (VI).
The higher the VI the lighter the oil will be on start-up.

For your Honda CRV I believe it has been back spec'd for the 0W-20 grade. The OEM 0W-20 oils made by Toyota, Mazda, Mitsubishi and Honda are high VI oils especially the Toyota and Mazda 0W-20 oils. So you could likely use one of those oils.

For your Jeep which is spec'd for a 30wt oil, unfortunately there are very few high VI 0W/5W-30 oils available. Havoline 5W-30 synthetic has one of the higher VI's (177) but not by much.
You could blend you're own 200 VI 0W-30 as mentioned below:

https://bobistheoilguy.com/forums/threads/caterham-blend-mobil-0w40-sm-tgmo-0w20-sn.198118/
If you did I'd suggest a heavier 60/40 blend.

So short of blending your own high VI 30wt oil, just using a synthetic 5W-30 is about as light an oil on start-up as you're going to get in an OTC motor oil.

 

[CATERHAM]

Correction, I meant to say, "all oil is too thick even at 100F".

 

[Mike2914]

Wow, thanks for all the responses! Rather than quote/reply to individuals, I'll just try to generically respond.

Even though the the CRV does have an oil life monitor, I'd feel better just changing it every 5k miles. Maybe later on down the road I'll get sophisticated and see how much life I can squeeze out of my oil but for now the cost impact of changing more frequent is pretty low. On that note, I plan on changing both of the cars at 5k mile intervals.

Thanks for the note about Jeep 4.0s not liking Mobil oil...I'll try to pick any other brand just to be safe.

Regarding synthetic vs mineral oil, 'Oil university' basically says synthetic has better additives and lower viscosity when cold. Since 90% of engine wear occurs during startup, the lower the viscosity at 'cold', the better. Synthetics also tend get in tighter spaces and cling to your engine parts which helps with lubrication during startup (or so the article says). I'd just like to state that I'm a cheap guy - not trying to spend anymore than I have to, but also don't want to be penny wise and pound foolish. I know neither of my cars require synthetic, but if they really decrease engine wear then I'm all for spending a little extra. The prices at Walmart looked pretty reasonable (~30 for 5 quarts) of synthetic vs ~20 for mineral.

On to oil weights, are you guys suggesting to use a 0W oil if going synthetic and a 5W oil if going mineral? I still don't understand why I wouldn't want a 0W regardless? Any if anyone can help with the 20 vs 30 for the CRV and Jeep...I didn't get what DrDusty was saying. What is CAFE stand for?

 

[Quattro Pete]

Originally Posted By: Mike2914
On to oil weights, are you guys suggesting to use a 0W oil if going synthetic and a 5W oil if going mineral? I still don't understand why I wouldn't want a 0W regardless?

You would want it, but there are no mineral 0w-XX oils out there that I'm aware of. If you're going with mineral, 5w-XX is as low as you're going to get.

 

[Kuato]

CAFE = Corporate Average Fuel Economy.

 

[Mike2914]

Thanks all. So here's what I'm thinking.

Walmart likes Mobil1 it appears I'll go with that for the CRV.

CRV
Mobil1 0W-20 Advanced Fuel Economy Full Synthetic Motor Oil $22.47
Purolator filter
5k oil change interval

Which one do you think for the Jeep?

Jeep
Quaker State Full Synthetic 5W30
Valvoline Max Life Full Synthetic 5W30
Castrol Edge with Syntec Full Synthetic 5W30
Purolator filter
5k oil change interval

Also, do I run any risk of damaging the engine using a 0W-20 oil in the CRV when it calls for 5W-20? Based on oil university I would say no but thought I'd double check before messing with the wife's car...

 

[Kuato]

Originally Posted By: Mike2914
Thanks all. So here's what I'm thinking.
...
Which one do you think for the Jeep?

Jeep
Quaker State Full Synthetic 5W30
Valvoline Max Life Full Synthetic 5W30
Castrol Edge with Syntec Full Synthetic 5W30
Purolator filter
5k oil change interval


I'm partial to the Valvoline. Edge is probably a better oil, but I'm a BP hater.

Originally Posted By: Mike2914

Also, do I run any risk of damaging the engine using a 0W-20 oil in the CRV when it calls for 5W-20? Based on oil university I would say no but thought I'd double check before messing with the wife's car...

Nope, no risk at all, unless the Honda is still under warranty.

 

[AmishFury]

for a jeep with a 4.0 and 5K intervals i wouldn't waste money going full syn unless you're going to rethink the OCI

also where on a 97 ZJ would it say 5w30? last i checked the manual for mine recommends 10w30 (though a 5w30 is acceptable)

my recommendation for your jeep would be QS Defy or maybe consider a HDEO

 

[Kuato]

Originally Posted By: AmishFury
for a jeep with a 4.0 and 5K intervals i wouldn't waste money going full syn unless you're going to rethink the OCI

also where on a 97 ZJ would it say 5w30? last i checked the manual for mine recommends 10w30 (though a 5w30 is acceptable)

my recommendation for your jeep would be QS Defy or maybe consider a HDEO


My owner's manual for the Gr Cherokee says the same(10w30), unless it is below freezing. I have been using 5w or 0w30 for 100000 miles now in all seasons. A little extra flow in startup certainly doesn't hurt.

 

[901Memphis]

If your going with 5k intervals you don't need to get crazy, any of the API SN oils will do that no sweat. Mobil 1 is a cheap choice at under $22 a jug, so i would probably go with that.

Of course if you went 5k on something like pennzoil ultra, you wouldn't be the only one.

 

[Ken2]

Mike, "Motor Oil University" was written by a cosmetic plastic surgeon, Dr. Ali E. Haas, from Venice, Florida. He has some good stuff in his article and some stuff that is simply wrong or not suitable for all engines.

The oil viscosity an engine needs is determined at the design stage of the engine. The film strength of the oil varies with the viscosity, other factors remaining equal. How much film strength is required depends on the load on the bearings and the surface area of the bearings to carry that load, among other things. It isn't all about the power--a very large diesel engine that puts out 7,500 hp per cylinder uses 30 wt crankcase oil. a 50,000 hp jet engine uses 5 wt. oil.

So, follow your engine makers' recommendations. Synthetic oil is better in a few cases, mainly for frigid winters, Death Valley summers, and somewhat longer oil change intervals. You will find no advantage in a 0W oil in your climate. Look how many cars are driving these days with 200,000 or 300,000 miles on them and just ordinary maintenance, and sometimes not even that.

 

[CATERHAM]

Originally Posted By: Ken2
Synthetic oil is better in a few cases, mainly for frigid winters, Death Valley summers, and somewhat longer oil change intervals. You will find no advantage in a 0W oil in your climate. Look how many cars are driving these days with 200,000 or 300,000 miles on them and just ordinary maintenance, and sometimes not even that.

You couldn't be more wrong.
Many manufacturers now specify 0W-XX synthetic oils and it has little to do climate or the oil's ability to pump at -40 degrees but rather about being as light possible at more typical start-up temp's. That's why OEM 0W-XX oils have a high viscosity index, to be as light as possible on start-up and during the warming-up period. The main purpose is to save fuel but it also makes for a more efficient running engine, with less wear, greater power and driveability.

It's the last three reasons that I prefer high VI oils.

 

[Clevy]

Originally Posted By: Mike2914
Wow, thanks for all the responses! Rather than quote/reply to individuals, I'll just try to generically respond.

Even though the the CRV does have an oil life monitor, I'd feel better just changing it every 5k miles. Maybe later on down the road I'll get sophisticated and see how much life I can squeeze out of my oil but for now the cost impact of changing more frequent is pretty low. On that note, I plan on changing both of the cars at 5k mile intervals.

Thanks for the note about Jeep 4.0s not liking Mobil oil...I'll try to pick any other brand just to be safe.

Regarding synthetic vs mineral oil, 'Oil university' basically says synthetic has better additives and lower viscosity when cold. Since 90% of engine wear occurs during startup, the lower the viscosity at 'cold', the better. Synthetics also tend get in tighter spaces and cling to your engine parts which helps with lubrication during startup (or so the article says). I'd just like to state that I'm a cheap guy - not trying to spend anymore than I have to, but also don't want to be penny wise and pound foolish. I know neither of my cars require synthetic, but if they really decrease engine wear then I'm all for spending a little extra. The prices at Walmart looked pretty reasonable (~30 for 5 quarts) of synthetic vs ~20 for mineral.

On to oil weights, are you guys suggesting to use a 0W oil if going synthetic and a 5W oil if going mineral? I still don't understand why I wouldn't want a 0W regardless? Any if anyone can help with the 20 vs 30 for the CRV and Jeep...I didn't get what DrDusty was saying. What is CAFE stand for?


The comments about better additives isn't quite true,nor is the cling theory. In fact pao basestocks aren't polar at all. So with that syn as an example the comment is wrong.
Believe it or not mineral oil is polar. So in essence all things being equal an engine is better off at start up with a conventional vs a pao syn.
Poe is polar though,so the comment about cling is accurate when an ester base is included in the formulation.
And as far as the additive comment goes most adds arent soluble in pao,however poe and mineral basestocks have no additive solubility issues
So in actual real world use an oil that combines all these basestocks may in fact be stronger in terms of additive delivery,polar attraction which can lessen start up wear due to the oil cling.
I used to think that pure pao or ester was better than having the oil cheapened by utilizing mineral basestocks however as I've learned here at bitog I've come to the conclusion that an oil that combines all these ingredients may in fact perform better in service due to the balance and synergy of the components working together.
But I refuse to out the mos2 away. Synergy be darned
A.E haas did write a very helpful article and it does initiate the newbs and helps them understand the basics however what was written so many moons ago may no longer be accurate but was accurate at the time of writing.
You gotta give the guy credit. He is using some exotic expensive vehicles as test miles for the thinner is better data points.
Wasn't he using a 20 grade in a Lamborghini or Ferrari or something. He also collected a lot of data and shared it with us to help open us thicker is better guys minds.
Anyways in the end it is the entire formulation that does the work and once blended could very well be much more than the sum of its parts.
This whole idea is what's led me to not be so closed minded when it comes to today's oils. They are a balanced tightrope walk,trying to do so many things all at once and the cannot be great at everything so they must find their happy medium.
This is why there is no best oil. Applications vary so much that not one oil could succeed in doing everything perfect. Some engines need more detergency,some need a thicker boundary layer,some need to have specific volatility because the engines run so hot the oil just evaporates leaving deposits behind.
Some need to burn absolutely clean because the design of the engine uses the oil as the combustion chambers seal(think wankel)
Oil is a balancing act. Find out what your engine needs most from an oil and find one that achieves them the best.
Zddp in flat tappet cam break in is another good example.
Some engine builders flatly refuse to use an oil with any friction modifiers during break in because they feel the rings won't properly seat(high tension rings) and some guys and oems feel the need to ship with a special high moly break in oil and insist on running it out to the full interval dictated by the oil life monitor(think low tension rings)
Each engine has its own dynamic and engineering complications(think BMW and bad bearings requiring a special custom made oil in the 10w-60 flavour).
Once it's weaknesses are exposed tailor your oil choice to one that's formulation is meant to lessen the potential harmful effects.
Just my long winded and summary of how bitog took me from running rotella 5w-40 in everything to the well rounded junior backyard tribologist I am today.
Special thanks to all the guys who took the time and had the patience to come up with an explanation I could understand.
I'm confident it wasn't easy.