Thick oil...Or thin...???

userfriendly · Oct 22, 2003

Jelly;
I think you have some good points in the above post, but a 15Wxx may not have the cold flow performance that people in other regions require.
The 15.5 cSt part? yea, a little over the top, but the HDMOs start off at the high end of the SAE 40 scale, so they will not thin out of the next grade lower toward the end of their service life expectancy.
A single grade SAE 40 without VI improvers may start out around 14.5 cSt when fresh.
I believe that the correct balance between engine efficiency and wear occures when the engine oil is operating at a temperature that puts the viscosity between 11.5 and 13.5 cSt.

Jelly · Oct 22, 2003

quote:

Originally posted by userfriendly:
Jelly;
I think you have some good points in the above post, but a 15Wxx may not have the cold flow performance that people in other regions require.
The 15.5 cSt part? yea, a little over the top, but the HDMOs start off at the high end of the SAE 40 scale, so they will not thin out of the next grade lower toward the end of their service life expectancy.
A single grade SAE 40 without VI improvers may start out around 14.5 cSt when fresh.
I believe that the correct balance between engine efficiency and wear occures when the engine oil is operating at a temperature that puts the viscosity between 11.5 and 13.5 cSt.

Geezzzz friendly, we're going back and forth here on different threads...

Yes, I fully understand that a 15w40 is just too thick for a good deal of the country come the cooler months. Heck, I don't even know if it will work out for me as I've never ran a 15w40 in winter...soon to find out though.

You're a very opinionated person friendly, and so am I...yes, 15.5cSt is a little too thick, but I still stand by my opinion of liking to have a thicker fluid film between moving parts. Yes, the thicker film will increase internal engine friction, but that's enough of a downside for me too make a switch to a thinner-oil.

...The only thing that will make me change at this point would be poor cold weather performance come the next few months.

Dr. T · Oct 22, 2003

I agree...there's not much there to back things up.

However, I feel that used oil analysis don't show the whole picture. Every time I ask about consumption, nobody bats an eye. Do you think it's normal to use a 0-20 because the manufacturer says so and then in the same breath tells you it's completely acceptable to add 1qt every 1k mi?

How do used oil analysis account for consumption? How do they account for sludge? Varnish? Baked on garbage that rob you of hp after 100k mi.? Where do the burnt by-products of oil consumption go? In a used oil analysis report? I don't think so. Hey, maybe we'll have worse used oil analysis numbers on 50 weight oils because the wear numbers aren't being burnt on the inside of the engine...ie. which figures on a used oil analysis show that the oil type/brand/viscosity is reponsible for stuck rings on a Saturn?

We've seen 3MP's study...do you think that engine is fine? Then we should all simply do 18k mi. oil changes with Mobil 1 5w30. Close this board. No?

What about personal experiences with VW or BMW's that are properly maintained, yet require overhauls because of 30 weight oils. Mine was one of them.

I will predict that what will be found is that unless your car requires a 50 or 60 weight oil because of power output (will suffer catastrophic failure), the used oil analysis won't be entirely conclusive. However, you will have increased engine cleanliness and hence, longevity. Again, what's the alternative? 1. 3k oil changes 2. auto-rx.

Does the engine size/type matter? Yes and no. Yes, because some engines run at low rpms and temps and perhaps don't require a 60 weight. On the other hand, 40 or 50 weight oils have more cojones when you need it...ie. full throttle runs. I agree with using climate/ambient temperature to select grade. ie. in Mexico City Dodge minivans run 15-40,15-50...why? Because it's not a place where -25C is a problem.

Happy motoring...

Patman · Oct 22, 2003

Dr.T, you seem to be stuck on the fact that 5w30 and 10w30 oils will cause an engine to build up a lot of sludge and varnish inside, but that's simply not the case. Unless someone is severely overextending their oil or they've got a mechanical condition, the use of 30wt oils does not cause an engine to get dirty. Just ask anyone on this board who has removed their valve covers or torn down an engine run on nothing but 5w30/10w30. And what about all the Amsoil testimonials out there where someone runs their 5w30 for 400,000 miles and takes a look inside the engine to find it perfectly clean?

I just don't know where you get this idea that thick oils mean the engine will stay cleaner? Perhaps with your engine the thinner oils did this, but then again maybe you weren't using such high quality oils? So it's the brand to blame for your varnish, not the viscosity.

userfriendly · Oct 23, 2003

Patman;
Your right, viscosity and deposits are two seperate topics, but not completely un-related.
If an engine oil is too light for the temperatures it encounters, or has a low vapor or flash points, it could result in increased consumption and deposits including varnish.
The viscosity of single grade engine oils are usually published at four temperatures.
1. The cSt at 40C
2. The cSt at 100C
3. The HTHS at 150C
4. The minimum temperature pour point/pumpability
In addition to those four, multi grade engine oils have two more specified cold performance typicals, published at temperatures depending on the xxW designation:
1. The CCS, cold crank simulator
2. The cold pumping cSt viscosity
My question to you is:
Unless you know what temperature your engine oil or anybody elses is operating at, how can you determine what viscosity is needed by those engines?
For example a Ford Focus engine may never see oil temperatures above 195F and live quite comfortably on an SAE 20 engine oil.
A Chev truck with a 4.3 V-6 and towing, may see engine oil temperatures as high as 260F, and not live very long with an SAE 30 grade of engine oil.
The point being is that at 195F, SAE 20 (or 5W20) is thicker than SAE 30 (or 10W30) is at 260F.

[ October 23, 2003, 04:36 PM: Message edited by: userfriendly ]

geeeman · Oct 23, 2003

So ........ mount a decent oil temperature gauge, make notes about average, peak oil temps, take ambient temp into account, then pick your viscosity...? Seems really simple...

Realistically, anyone serious about their engines should know their oil temps...

Anybody know what the average oil temp is on a new Civic or Focus? Kinda curious, given the 20w recommended oil.

Patman · Oct 23, 2003

quote:

My question to you is:
Unless you know what temperature your engine oil or anybody elses is operating at, how can you determine what viscosity is needed by those engines?

I do have a general idea of how my oil temps run though, which is one of the reasons I knew that a thicker 30wt oil, one that was almost a 40wt, was going to give me better results. I knew with oils closer to 10cst, it was too thin to protect me when my oil temps got above 230F, which I know happens a lot in the summer. In fact I suspect in heavy traffic my oil approaches 300F, as it was hot enough to melt one of my sample bottles when I drained my oil!

buster · Oct 23, 2003

I think Pepboys sells cheap oil pressure/temp gauuges. Are they any good?

Patman · Oct 23, 2003

quote:

Originally posted by buster:
I think Pepboys sells cheap oil pressure/temp gauuges. Are they any good?

Probably not, if you're going to get an oil temperature gauge, go with Autometer or VDO.

I'm thinking of getting one, I just don't know where to mount it inside my car without it looking out of place.

Dr. T · Oct 23, 2003

Honda Civic...my brother just failed emissions yesterday after using Mobil 1 5w30 for the past 150/180 k mi. in his `92...told me the car started burning the M-1 for the past year and a half or so....because that 30 weight protected so well. He changed it every 3-5k mi.. Guess, it's time for some engine work...however, there's no more warranty...Honda's fault? Maybe it would have faired better if he used 5-20??

Do you guys think combustion chamber/piston temps are different in a saturn than a vette??? Coolant temps are different...but, can you put an oil temp. sensor right in the piston? Are the combustion temps. actually less in a 4 cyclinder than in an 8?

Jelly · Oct 23, 2003

Possible that after 180,000 miles, the O.E. emissions equipment is pretty much toast?

jsharp · Oct 23, 2003

quote:

Originally posted by Dr. T:
Honda Civic...my brother just failed emissions yesterday after using Mobil 1 5w30 for the past 150/180 k mi. in his `92...told me the car started burning the M-1 for the past year and a half or so....because that 30 weight protected so well. He changed it every 3-5k mi.. Guess, it's time for some engine work...however, there's no more warranty...Honda's fault? Maybe it would have faired better if he used 5-20??

Do you guys think combustion chamber/piston temps are different in a saturn than a vette??? Coolant temps are different...but, can you put an oil temp. sensor right in the piston? Are the combustion temps. actually less in a 4 cyclinder than in an 8?

At 10 years old and 180K miles it's no surpise it didn't make it through emmisions testing. Lots of things can cause that.

Of course the combustion temps are roughly the same no matter the engine size or number of cylinders. Probably roughly the same with coolant temps too depending on the engine. At the same time, I'll bet running a heavier oil of the same type like Mobil 1 15W-50 would have made his oil temperature higher. Is that a good thing long term?

I've yet to see any definative study settling the heavy/light oil argument. My opinion is that for every engine and set of operating conditions there is an optimum weight. used oil analysis, oil temp readings, watching oil usage and wear all all ways to help determine this short of running things until they completely wear out and then trying somethign different...

geeeman · Oct 24, 2003

Failed emmissions does not always mean worn out engine... Catalytic converter prime suspect, O2 sensor, air filter etc...

Do a leak down test ( a type of compression test) and truly find out if the engine is tired... it might be something else...!

Does the car blow blue, or black or white smoke...if it doesn't smoke noticeably, it might be something minor.

Patman · Oct 24, 2003

I see lots of old Civics burning oil, and I don't think it's got anything to do with oil viscosity. You see many other cars on the road that don't burn oil, and they use 5w30 too.

I got stuck behind an old Civic this morning that burned a ton of oil too, everytime he got on or off the gas he gave out a big James Bond smokescreen. I see a lot of old VWs doing this too. It's a combination of engine design and neglect, not choice of oil or oil viscosity that causes these things to burn oil.

I can virtually guarantee you my wife's Civic will never end up with a fate like this. After using nothing but 5w30 so far (and now 0w30) it still does not use any oil at all between changes. The dipstick level does not change for the entire 5000 mile interval. Sure it's only got 47k on it, but if 5w30 was so evil like some of you think, then by now we'd be seeing some oil consumption don't you think? But yet it doesn't even need 100ml worth of top up oil during it's interval.

buster · Oct 24, 2003

My car burns oil and viscosity has nothing to do with it. It is very normal for certain engines to use oil, mine is one of them. I always have to add to up oil to it. Dr.T, we need some evidence of your claims about thick oils. Your always talking about how much better they are then thin so lets see some comparisons.

Sin City · Oct 24, 2003

180,000 km is only about 120,000 miles so I would agree that the 1992 Honda Civic should be in better condition than that.

Sin City · Oct 24, 2003

We have a fantastic UOA on a 2002 Honda Civic Si using 15W-50 Mobil 1.

We also have soom very good used oil analysis on Ford's and Honda's using 0W-20 and 5W-20. So far I would say that the evidence is inconclusive.

[ October 24, 2003, 10:09 PM: Message edited by: Sin City ]

Patman · Oct 24, 2003

quote:

Originally posted by Sin City:
180,000 km is only about 120,000 miles so I would agree that the 1992 Honda Civic should be in better condition than that.

The car he's talking about does have 180,000 miles on it though, I believe he's converted the mileage from km to miles, it looks that way based on his post.

Drew99GT · Oct 20, 2008

Is 5w-20 too thin? Or should I just go ahead with 30w-80 my grandpapi told me to use? This is for an 09 Civic. It says 5w-20 on the oil cap, but I'm scared to use it. Just seems way to thin. I know they only use these thin oils for fuel mileage, sacrificing wear protection.

sunfire · Oct 20, 2008

Originally Posted By: Drew99GT
Is 5w-20 too thin? Or should I just go ahead with 30w-80 my grandpapi told me to use? This is for an 09 Civic. It says 5w-20 on the oil cap, but I'm scared to use it. Just seems way to thin. I know they only use these thin oils for fuel mileage, sacrificing wear protection.

haha... powertrain warranty is void.

Thick oil...Or thin...???

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