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

[clemsonfor]

I use a name brand of exactly the recommended weight and class of oil in each of my engines. I haven't had to add oil between changes to an engine in 30 or 40 years. Is it ok to go against recommendations? Probably, but it wouldn't be worth it to me to try it, based on past experience. Engines are expensive.

Just useing the right oil and a name brand (does not matter really) but that does not stop oil buring issues. this can be brand and engine specific as well as how hard your dive a car and how long you keep it.

 

[clemsonfor]

I wouldnt use an XXw40 ins something calling for an XXw30 or vice versa.

30 is lighter, 40 thicker. Engineers base recommendations on internal clearances and bearing clearances in the engine. Too thick may cause too much pressure and too thin may not be enough.

The first numbers are the winter value and dont necessarily indicate the oils thickness. Rather it indicates its resistance to thickening when cooled. Lower numbers resist thickening better.

I would first question why you "think" you need so many oils. Why stock both 5w40 and 15w40 when 5w40 is all you need.

And why stock 3 different 30w oils when 5w30 will work in all applications.

I use 3 different oils.
0w20 synthetic in the wifes hemi which calls for a 20w oil
0w30 synthetic in the two cars which call for a 30w oil
5w40 Synthetic T6 in all the diesels

This!

 

[clemsonfor]

I just recently switched my 3 diesel tractors over to 5W40. They all had started hard in the winter, but I was hesitant due to their age ('77, '84, '86) However, no leaks so far. I am not convinced that 5W30 would hold up to the summer heat while mowing in my 3 gas mowers ('64, '67, '67). I have been using the 10W30 in my Buick LeSabre, just seemed that thicker oil would be good for it.

You dont understand oils then??? 5w30 and 10w 30 are just as thick at operating temp. Just when poured cold is the 10 going to seem thicker than the 5. Just sitting in a pan is not when things leak its when running and oil is slung all around and on all the seals and gaskets . At that temp there just as thick.

 

[clemsonfor]

Your logic is flawed as are many others.

5w30 is NOT thinner than 10w30
5w40 is NOT thinner than 15w40

They are the SAME.

Last number (after the w) is the oil thickness. The first number tells you how much it thickens when cold. That is why you don't notice any additional leakage in the old tractors. Because you are running the SAME weight oil in there. Just a little better performing as it don't thicken up "as much" when cold as 15w40 does.

LD1, thanks for clarifying that. I had always assumed 5Wxx was thinner than 10wxx. You really do learn things every day. Will, I also have that cartridge filter set up on my wife's Corolla. They are kind of a pain. I discovered that the oil filter wrench for my LeSabre fits the cartridge housing of the Corolla real nice. Everyone else, thanks for the feedback. I think what I am going to do is, use 5W40 synthetic for all my tractors and small engines. And 5W30 synthetic for all of my vehicles, which are all gasoline fueled. I can handle just 2 weights of oil on the shelf.

right

 

[arrow]

Might have been in existence? 60's?

Try 1913 for the patent. Germany was using syn oil products in ww2.

Bergius , coal-> fuel direct.

In our shop back in the early 60's, it may as well not have been in existence at all. I used "might" because I didn't know when it came to be. I just knew it existed for a long time. Certainly the advances in oil formulations have made all oils a different animal even from year to year.

 

[oldpilgrim]

The Toyota Tacoma 4 cylinder pickup comes with 0W20 synthetic from the factory and a 5,000 mile oil change interval. Maybe it has to do with the additives required for the "0" rating and mentioned earlier in the thread? Owner's manual says 5W20 is OK but only on a temporary basis and to switch back to 0W20 ASAP.

I would agree that I could go longer on an oil change.

the V8 Tundra comes with 0w20 but a 10,000 oil change interval....maybe because it holds 7+ qts of oil ?

 

[big bubba]

just a curve ball in this oil war debate acknowledging my own ignorance in light of these replies...one hears all sorts of extended oil changes regarding synthetic, from 5k to 15k in vehicles and tractors, & in semi's much more... to what extent does the volume of oil capacity in a given engine oil sump relate to frequency of change? so in a v8 we go much further.....proportionally, in that same way a 4 cyl engine or even lawnmower? it's easy to say go longer w/syn, but is frequency of change extended across the board regardless of the engine oil capacity? think i'll change a bit more frequently in my zero turn compared to my road vehicles using the same T6 rotella on a comparative scale. sorry for being pedantic, but i think smaller engines need more frequent changes in the equation....your thoughts?

 

[RalphVa]

A larger sump would dilute soot from piston ring blowby and enhance the ability to have a longer oil change interval. However, the interval on our Jetta TDI is 10k miles, and its oil capacity is only 4 or 5 quarts. I'd think the oil change interval on the V8 gas Tundra should be safe to 15k miles. That's what it is on gas Mercedes. VW have never had an engine problem due to lubrication using the 10k interval on the TDIs.

Ralph

 

[big bubba]

A larger sump would dilute soot from piston ring blowby and enhance the ability to have a longer oil change interval. However, the interval on our Jetta TDI is 10k miles, and its oil capacity is only 4 or 5 quarts. I'd think the oil change interval on the V8 gas Tundra should be safe to 15k miles. That's what it is on gas Mercedes. VW have never had an engine problem due to lubrication using the 10k interval on the TDIs.

Ralph

thanks. contaminants vs oil capacity is something i haven't decided on yet regardless of oil type. think choosing the right oil type is more important than a question like mine. best regards....

 

[bdog]

thanks. contaminants vs oil capacity is something i haven't decided on yet regardless of oil type. think choosing the right oil type is more important than a question like mine. best regards....

Thats assuming the same engine size. I would think a large displacement V8 would generate more soot than a tiny four cylinder in an economy car thus negating the dilution effect of a larger sump.

My Kenworth has a 10.8 liter engine and holds 44 quarts. My wife's car has 3.5 liter engine and holds 5 quarts. The Kenworth has three times the displacement but holds nearly 9 times as much oil. Maybe that is why the big rigs have the longer oil change intervals because the displacement to oil capacity ratio.