5W40 synthetic diesel engine oil in a modern gasoline engine?

[Diamondpilot]

Significant truth to that idea. While additives can be replenished, it is the viscosity improvers that actually shear and break down. You are correct, the base oil itself doesn't break down. But VI are in a class by themselves compared to additives that control oxidation, soot control, etc and those that act as detergents and such. One can replenish those, but one cannot just replenish viscosity improvers. They are an integral part of the motor oil as it was developed. The only way to make an oil longer lasting in that regard, is to have a base oil that significantly reduces the need for VI. But to do that, even with PAO Group IV synthetics, you greatly restrict the limits of the cold flow. For instance, while there are many PAO full synthetic 30w oils that qualify as 10w30 on their own without any VI, as you go to something like a 5w30 and even further with a 0w30, the use of viscosity improvers is the only way to get to those low cold flow levels. And filtration or additive replenishment will never compensate for such things a fuel dilution. So either via fuel dilution or VI shearing, once an oil goes out of grade, it has to be changed.

My ex father in law, who worked for Pennzoil, said the biggest factor on modern vehicles that increased oil life and engine life isAIR filtration.

Makes sense. All a engine is really is a air pump. The vehicles up to about the 80's has crappy air filter systems. Today's small engines up to heavy equipment have very tight air filtration systems.

Chris

 

[arrow]

My ex father in law, who worked for Pennzoil, said the biggest factor on modern vehicles that increased oil life and engine life isAIR filtration.

Makes sense. All a engine is really is a air pump. The vehicles up to about the 80's has crappy air filter systems. Today's small engines up to heavy equipment have very tight air filtration systems.

Chris

As a former high performance engine builder (even though 1/4 mile runs did not rely on serious filtration), side discussions in the shop that included much more experienced mechanics than myself, always pointed to the air filter being the most important filter in a car. As a then young mechanic, this was drummed into me time and time again. So much has changed since then that discussions on the subject could be all encompassing.

 

[WilliamBos]

I do the same, makes life easier.

I keep 5w-30 oil for the cars and truck..
and Rotella T6 synthetic 5w-40 goes in the tractor, zero turn, ATV, motorcycle, push mowers, generator, water pumps, Etc.

 

[clemsonfor]

Speaking of filters, On my 95 Dakota, the filter looks like a piston, size wise. The filter on my Forester is a bit larger than a shot glass. Makes me think residual burn particulates in gas engines are not the issue they used to be. 4 .2 ots in rthe Soob and 5 qts in the Dak.

This is not the case. Many companies use the same filters they have for years. My 4.7L toyota v8 uses the same filter that an 80s model Hilux 4cyl pickup use to use. Its tiny compared to the motorcraft 1a or fram Ph8a the common old big ford filter that every thing took. I had that same filter on my old 4cyl for tempo as did 90% of fords fleet back 20-30 years ago! Same filter went on the 2.3L the 5.0, the winsor 351 the ford 460 etc

 

[Texasmark]

Used to be I would have used the 5w-40 in everything besides my tractors. However, back in '07 My Ram owner's manual said to use 5w-30 as the oil pump was built for that oil....no more heavy oil for heavy duty service it said.

In '09 My Hemi ran on 20 and said the same thing.

My '11 Silverado says the same thing on 30 but it has to be semi-syn....that's ok cause I use Mobil 1 0w-30.

Grand daughter's Honda CR-V says 20 full syn. That's ok cause I run Mobil 1 0W-20.

I don't think we can go back to yester year practices.

 

[WilliamBos]

I was consideting it for my 04 GMC, just because everything here runs T6, atv, rototiller,pressure washer, tractor. When I traded off the 04 for my 11 I started reading up on VVT. GM does not recommend 40 weights for these LS engines.

 

[oldpilgrim]

my Tundra says use 0w20. I understand clearances in the motor are really tight and it's not a good idea to use anything heavier. I wish I could as I'd use it in everything. It would make home oil 'inventory' much easier.

 

[sixdogs]

my Tundra says use 0w20. I understand clearances in the motor are really tight and it's not a good idea to use anything heavier. I wish I could as I'd use it in everything. It would make home oil 'inventory' much easier.

I have two Tundras and after a great deal of research and talking with mechanics and such, I went with a heavier oil and have done this for years . It is my understanding the thinner oil helps met energy efficiency standards. The owner's manual says that we use should use a heavier oil if you tow, and I do.

I use 5W30 synthetic in the summer and 5W20 in the winter. It's a mild climate here and I park in a garage.

A heavier oil quiets the engine quite a bit and no more "clacky" or diesel sound on start up.

 

[DEWFPO]

It's interesting that in Europe, the same vehicles we have here with the same motors (not all the motors are the same but many are), are spec'd for much heavier oils there. They have the same tight tolerances in the motors, dual variable valve timing, catalytic convertors and the like. Some have even tougher emissions regulations but their manuals say it is o.k. to run 40 and even 50 weight multi-viscosity oils under certain circumstances.

Go Figure.....

DEWFPO

 

[davesl708]

My Subaru prefers 5w-30 but clearly states in hot climates or towing use a heavier oil up to 20w-50.
I rarely get below zero here but do get to 100 so I run Rotella T6 5w-40 year round. Same for My BX