?? About using 15w40 in gas engines

[haley10]

quote:

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Originally posted by Blue99:

Also, a bit off-topic, but does the Chevron bulk oil in your area of Georgia get shipped in all the way from California?

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Chevron has huge facilities on the Mississippi Gulf Coast (Pascagoula), so I would doubt it.

 

[rainman49]

Dang, I didn't know I was screwing up so badly. I've been running mostly Castrol GTX 20w-50 in my '88 F150 with 5.0L engine since I changed the factory oil. I said "mostly." It has a 6-quart sump, so I'll typically use 4 or 5 quarts of 20w-50 and one or two quarts of synthetic, either M1 15-50 or Syntec 5-50.
I've only got 445,000 miles on the 5.0 that's never had the valve covers removed, so I guess I've ruined the engine

.
Now, I do live in L.A. (Lower Alabama), which means I can use a thicker oil. I wouldn't have tried it if I lived up north (of Birmingham).

 

[Jimbo]

Recommended oil viscosity seemed to take a jump as emission-controlled, but still carbed, engines started to run hotter. Todays more robust oils combined with fuel injection calibrated for lean-of-peak mixtures may be permitting the use of thinner grades again. Bearing clearances have not changed over the years.

A sampling from owners manuals for cars in our family.

1955 Chevrolet:
20W-20 primary
30 summer only

1968 VW:
20w-20 winter only
30 otherwise

1972 Buick:
5W-20 winter only
10W-30 or 10W-40 otherwise

1987 Dodge light truck:
A complicated scale based on temperatures
with both straight 30 and 15W-40 recommended
for summer.

1992 BMW:
Another complicated scale ranging from 5W-30 to 20W-50.

 

[TR3-2001SE]

I conferm you will lose gas milage. The worst I ever got from my honda was 26.5. It is now giving 25.5 with delo 400 15w-40. It will get Mobil 1 5w-30 as soon as the auto-rx rinse is complete. Weather is very warm hear so the startup should be fine with 15w.

 

[Last_Z]

quote:

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Originally posted by Ugly3:
I just don't understand. The car maker has tested all kinds of oil and comes to the conclusion that 5w20 is the recommended oil. They know it is hot in the south and cold in the north. They know the folks occasionally tow a trailer. They know all this and now we decide that 15w40 is what is "really" needed. It just makes no sense to me.

The thinest oil you can find (0w or 5w) is too thick at startup and we think a 15w is better.

The car maker says w20 is fine for the engine. Millions of engines ran on 20 weight oil in the 50's and 60's, they didn't blow up. When Mobil 1 came out in the 70's it was 5w20 because they did a study and determined that w20 was fine for the vast majority of applications. Now we, with our infinate wisdom say they are all wrong and start running w30 and w40 oils.

Old perseptions die hard.

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Ugly,

I take what car manufactures say with a grain of salt.
-Chevy decided to change the glue used to attach the roof panel on my Z28. It seems little to no research and testing was done. The glue seeps through the fiberglass and contacts the paint from underneath......the paint is all bubbled up.
-Toyota didn't see the sludge problem on the 3.0L engine coming.....or did they?
-Why would they put a cr@ppy 10-bolt rear end on a very potent sports car (LS1 F-Body)
-Fords are plagued with electrical problems.....they set themselves on fire. Who did the testing?

I don't believe manufactures (at least domestics) have consumer's best intentions. I do believe the 5W-20 move was mostly due to EPA pressure.

So anyway....to answer the original question. Will 15W-40 cause any harm? NO!!!!!!! Use common sense though. It won't work in N. Dakota in the winter. Mileage "may" be affected some.

 

[99]

quote:

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Originally posted by Last_Z:
-Why would they put a cr@ppy 10-bolt rear end on a very potent sports car (LS1 F-Body)

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I don't know why GM didn't develop a modern day 12 bolt for those cars way back when they first tossed the LT1s in them in 93. The 10bolt has always seemed out of place on the 93-02 F bodies because the engines and 6spds have been pretty stout.