Wear or Gas Mileage

Al

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Jun 8, 2002
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Elizabethtown, Pa
I wonder how many Lube-savy BITOG viewers continue to opt for 20 wt. oil when its reasonably clear a 30 wt. will protect better. I say that bc the science of lubrication hasn't changed much in the last 70+years. (Not saying lub products have not gotten better). We are talking theory. And I am not faulting anyone that choses to use 30 wt or not use 30 wt.

Before manufactures went with 20 wt. oils I believe "the requirement" was that the vehicle engine would last 200K miles. It was determined that 150K miles was dooable.

The question is "why" do users go with 30 wt. Is it "economy" or warranty? Or something else.

I used the 20 wt. for my '19 Crosstrek and switched to 30 wt when I thought I would be keeping for a while (I didn't). I switched to 30 wt after 1000 miles on my '22Forester. And note the 20wt. oil can not adequately protect the Subaru FA Turbo engine...but it can protect the FA unturboed engine. Again not defending my actions. Strictly curiosity.
 
I dumped my factory fill in the Titan for 5w-30 and ran that for two changes. I decided to try a 0w-20 to see if there was a benefit in fuel economy. I didn't. I will now be going back to 5w-30 moving forward with the exception of some extra 5w-20 I have on hand I'll use in the winter months.
 
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I wonder how many Lube-savy BITOG viewers continue to opt for 20 wt. oil when its reasonably clear a 30 wt. will protect better. I say that bc the science of lubrication hasn't changed much in the last 70+years. (Not saying lub products have not gotten better). We are talking theory. And I am not faulting anyone that choses to use 30 wt or not use 30 wt.

Before manufactures went with 20 wt. oils I believe "the requirement" was that the vehicle engine would last 200K miles. It was determined that 150K miles was dooable.

The question is "why" do users go with 30 wt. Is it "economy" or warranty? Or something else.

I used the 20 wt. for my '19 Crosstrek and switched to 30 wt when I thought I would be keeping for a while (I didn't). I switched to 30 wt after 1000 miles on my '22Forester. And note the 20wt. oil can not adequately protect the Subaru FA Turbo engine...but it can protect the FA unturboed engine. Again not defending my actions. Strictly curiosity.
From the articles I've read, it's the 2.6cP HTHS that seems to define the floor for where you have to do "other things" to gain long term durability, such as utilize special coatings, implement wider bearings...etc. This is due to increased operation in mixed and boundary regimes vs hydrodynamic, and with components that historically had only operated in hydrodynamic. This is where many of the breakthroughs in additive technology have also had their focus, to deal with operation in mixed/boundary, but heavier oils like the xW-20+ grades have benefited from this science as well.

You have to remember that historically, oils were far inferior to those developed today in terms of stability, staying in grade, and the like, particularly when we are discussing the oils that dominated the oil change scene, which were conventional. Oils like Mobil 1, using PAO, were vast outliers and didn't represent the standard of the day.

A 5w-30 during the 70's, 80's and 90's, would have used primitive VII polymers that would rapidly shear, and cheap, light, and highly volatile base oils. It's quite likely that the engines of the day were actually running on an xW-20, and possibly one near the bottom of the range, despite the 5w-30 on the bottle. 10w-30's would have been a bit better, using slightly heavier bases.

The implementation of more stringent manufacturer and even API approvals in the last two decades for the North American marques, which aligns them more closely with the European OEM's, who started doing that in the 90's, has led to a dramatic increase in the quality of lubricants as well as pushing the oil companies to improve additives. This is also why it's very difficult to find a true conventional oil now, because they just lack the ability to meet the current performance requirements.

An oil like M1 EP 0w-20, using a personal example here, being ~70% PAO, is going to stay in grade and will be formulated with cutting edge AW and AF additive chemistry when compared to say SJ or SL vintage Castrol GTX, PYB, or Valvoline white bottle in the 5w-30 or 10w-30 grade, which will use light Group II and even maybe some Group I base stocks and a big shot of cheap VII.

Now of course modern xW-30's have improved too, benefiting from these same developments, but the above is more in reference to the perceived reduction in intended equipment operating life. I think you'll find that these engines that spec'd a conventional xW-30 were, in reality, spending most of the interval on a functional xW-20 due to VII breakdown. Shear resistance didn't even really become a thing until the Euros started rolling it into ACEA protocols and the Long Life oils started to appear on the scene.
 
I wonder how many Lube-savy BITOG viewers continue to opt for 20 wt. oil when its reasonably clear a 30 wt. will protect better. I say that bc the science of lubrication hasn't changed much in the last 70+years. (Not saying lub products have not gotten better). We are talking theory. And I am not faulting anyone that choses to use 30 wt or not use 30 wt.

Before manufactures went with 20 wt. oils I believe "the requirement" was that the vehicle engine would last 200K miles. It was determined that 150K miles was dooable.

The question is "why" do users go with 30 wt. Is it "economy" or warranty? Or something else.

I used the 20 wt. for my '19 Crosstrek and switched to 30 wt when I thought I would be keeping for a while (I didn't). I switched to 30 wt after 1000 miles on my '22Forester. And note the 20wt. oil can not adequately protect the Subaru FA Turbo engine...but it can protect the FA unturboed engine. Again not defending my actions. Strictly curiosity.
Well a V6 Accord goes 800,000+ miles on 20 grade with extended drains. How much farther would it go with 30 grade?

Honestly without knowing the bearing area, temperature and the HTHS of the lubricant (big difference between a 2.6 HTHS and 3.7 HTHS 20 Grade) it's all so much BS.
 
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Depends on the engine. I'd pretty comfortably use a 20 grade in a hybrid maverick knowing how i drive but i wouldn't want to use 20 grade in an ecoboost maverick. An NA port injected engine is a lot easier on the oil than a turbo gdi that will roast and dilute it.
 
I don't use 20 or 30 weight most of the time. Instead I use the same old 10w40 conventional I've been using since the 1970's and yes the conventional that I'm still using are conventional not synthetic blend since they've been stored in my garage since the 90's-00's. I'm guessing I've driven well over 1M miles since I bought my first car and have never had an engine failure. I drove an '88 Ford Escort with a 1.9L engine to 518K miles without an overhaul and it would have gone further if I'd have fixed other issues with the car. Even with '80's technology it routinely got 40-45 MPG and often saw highway speeds of 85-100 MPH. I see no reason to change what isn't broken. I'm not sure there's much if an fuel mileage to be gained by using lighter weight oils. I run 10w40 in my '16 Nissan Versa with a 1.6L CVT. The worst mileage I've got in it since purchase in Feb. 2019 is 42.345 MPG (hand calculated) in the dead of winter and my best is 58.908 MPG (hand calculated) in the summer heat.
 
This is also why it's very difficult to find a true conventional oil now, because they just lack the ability to meet the current performance requirements.
While I agree with everything you say, and your posts are always gold standard. I'll just point out that while not very common in North America, true conventional PCMO 15W40 are available all through Australia, New Zealand and most of Europe.

As you know, that thick Group-II base oil makes up for a lot, and often brings the Noack below 10% (MB 229.5 Noack territory), Shell Helix HX5 or Castrol GTX with SN-Plus/SN/ CF & Euro A3/B3 are two good cheap and common examples. They will be SP one days, but these basic products are always the last to be upgraded.

The diesel HDEO people, also saw the benefits of a conventional 15W40.

Yes, I agree, not suitable for cold winters. Yes I agree not available in North America. Just chatting that Group-II shines once you go thick (where Group-III can't reach).
 
While I agree with everything you say, and your posts are always gold standard. I'll just point out that while not very common in North America, true conventional PCMO 15W40 are available all through Australia, New Zealand and most of Europe.

As you know, that thick Group-II base oil makes up for a lot, and often brings the Noack below 10% (MB 229.5 Noack territory), Shell Helix HX5 or Castrol GTX with SN-Plus/SN/ CF & Euro A3/B3 are two good cheap and common examples. They will be SP one days, but these basic products are always the last to be upgraded.

The diesel HDEO people, also saw the benefits of a conventional 15W40.

Yes, I agree, not suitable for cold winters. Yes I agree not available in North America. Just chatting that Group-II shines once you go thick (where Group-III can't reach).
Yes, I didn't include HDEO grades, was speaking more to GF-5/GF-6 ILSAC grades like 5w-20, 5w-30. A 15w-40, as you noted, due to the narrow spread and 15W-xx Winter rating, can get away with using heavier bases, which in turn allows for more leeway on base oil selection.

Mobil's EHC bases (Group II+) are becoming more popular to be blended with Group III, and in many cases, replacing Group III in budget conscious blends. I think you've seen the data sheets I've posted from them on that?
 
I don't use 20 or 30 weight most of the time. Instead I use the same old 10w40 conventional I've been using since the 1970's and yes the conventional that I'm still using are conventional not synthetic blend since they've been stored in my garage since the 90's-00's. I'm guessing I've driven well over 1M miles since I bought my first car and have never had an engine failure. I drove an '88 Ford Escort with a 1.9L engine to 518K miles without an overhaul and it would have gone further if I'd have fixed other issues with the car. Even with '80's technology it routinely got 40-45 MPG and often saw highway speeds of 85-100 MPH. I see no reason to change what isn't broken. I'm not sure there's much if an fuel mileage to be gained by using lighter weight oils. I run 10w40 in my '16 Nissan Versa with a 1.6L CVT. The worst mileage I've got in it since purchase in Feb. 2019 is 42.345 MPG (hand calculated) in the dead of winter and my best is 58.908 MPG (hand calculated) in the summer heat.
I've come to the conclusion the main thing is to have oil in it.
 
it routinely got 40-45 MPG and often saw highway speeds of 85-100 MPH.

It might have gotten 40-45mpg and been driven 85-100mph but it didnt get 40-45mpg@85-100mph :LOL:

Fun Fact this is how pressure washers are rated.. 3500psi 2.6gpm. It might flow 2.6gpm(soaping) and 3500psi(0degree nozzle) but it wont do [email protected] ;)
 
Yes, I didn't include HDEO grades, was speaking more to GF-5/GF-6 ILSAC grades like 5w-20, 5w-30. A 15w-40, as you noted, due to the narrow spread and 15W-xx Winter rating, can get away with using heavier bases, which in turn allows for more leeway on base oil selection.

Mobil's EHC bases (Group II+) are becoming more popular to be blended with Group III, and in many cases, replacing Group III in budget conscious blends. I think you've seen the data sheets I've posted from them on that?
GF-5 & GF-6 what's that?
Is that what you buy when you can't get A3/B3 & A3/B4 ?

Just joking.....

Yes, you have posted those EHC data sheets before, but I would like to see them again if you have the time. They are buried deep in past threads
 
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