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

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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

Does Europe have C.A.F.E. standard such as we do? Lighter oils have much to do with increasing gas mileage as much as possible to boost up auto manufacturers numbers to meet these standards. Fortunately, oil tech has grown quite substantially to address these challenges. By 2025, our government is calling for auto vehicles to average 54.5 mpg's. This is the main thrust why we are seeing 1/2 ton trucks with 6 cyl engines attempting to boost mileage to 25 mpg's. You can bet your bottom dollar everyone will have some type of electronic car claiming to get 90-100 mpg to help increase averages.

 

[DEWFPO]

European CAFE equivalent is basically $7 a gallon fuel and very high taxes on large displacement engines. It essentially self regulates.

I agree, a lot of this has to do with U.S. CAFE requirements, but all I'm saying is that a good quality, modern 'heavier' oils will not likely destroy your engine as we are being lead to believe. I have run either 0W40 or 5W40 in everything I own (gas or diesel), (old or newer), (big or small), (on-road or off-road) for the last almost 15 years and have never experienced any issues relating to oil.

Just my 2 cents.

DEWFPO

 

[arrow]

European CAFE equivalent is basically $7 a gallon fuel and very high taxes on large displacement engines. It essentially self regulates.

I agree, a lot of this has to do with U.S. CAFE requirements, but all I'm saying is that a good quality, modern 'heavier' oils will not likely destroy your engine as we are being lead to believe. I have run either 0W40 or 5W40 in everything I own (gas or diesel), (old or newer), (big or small), (on-road or off-road) for the last almost 15 years and have never experienced any issues relating to oil.

Just my 2 cents.

DEWFPO

I have always felt that myself. Weightier oils never seemed to hurt anything but gas mileage and even that to only a slight extent. Heck, we used straight 50 w in the funny cars back n the 60's and some guys tried 80-90 weight gear oil (without great success I might add). Then, an engine had to last run after run as there were no "big stake" races back then as there are today.

 

[3930dave]

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

Some people had to learn how good modern factory air filter systems are, by getting UOAs done after "upgrading" to after-market air filtration systems. OE can perform very well, when left un-improved.

As well as that issue, I'd say the other big gain around that time frame was fuel injection - the increased accuracy of FI reduced fuel-in-oil contamination.

Fast forward a bit (Back to the Future )..... some DI gasoline injection systems have had issues with fuel dilution..... something to keep in mind, given the low OE viscosity spec of N. American engines being discussed.....

Rgds, D.

 

[Copperhead]

I often wonder why some have such a distain for better fuel economy a lighter oil would provide. Instead of a 15w40 or 5w40 for my Detroit Series 60 factory remanned pre-emission 12.7L in my semi truck, I use a 10w30 blend. I am all for a little better fuel economy. A simple .1 mpg increase nets a $600-$700 a year is fuel savings to me. A full 1 mpg increase? Well, you can guess how beneficial that is. A 10w30 provides more than ample protection for my motor. 476,000 on the motor now and it runs as strong as it did as a newly factory remanned crate motor. Oil samples the best I have seen of almost any similar motor, no leaks, only uses about 2 qts of oil in 25,000 miles, and it averages 20% better fuel economy than the commercial trucking sector national average.

I just have not been in the "thicker is better" oil mindset. Never saw any appreciable advantage. In over 5 million miles of commercial truck operation, I have never lost a turbo and the only major repairs of my last 3 heavy diesels was the first got one fuel injector and an accessory drive seal in 1.4 million miles of operation, the next got only a VG turbo actuator replacement in the 976,000 miles I owned it, and my current one, only two exhaust manifold bolts thus far in 476,000 miles.

All current heavy diesel OEM's are factory filling with 10w30 oils. Some even calling for up to 50,000 mile oil changes. I have no use for a 40w oil anymore. My gasser pickup gets a 5w30 that is recommended. I have no motivation to throw a 40w oil in it.