Motor oil: diesel vs gas trucks

[Dusty Britches]

Would you use the same weight motor oil in a diesel 3/4 ton truck as a gas 1/2 ton truck?

If so, what weight?

If not, why not?

 

[bigbull338]

Would you use the same weight motor oil in a diesel 3/4 ton truck as a gas 1/2 ton truck?

If so, what weight?

If not, why not?

if i was going to use a brand of oil in a diesel it would be rotella T oil.prolly 10w30 weight.but i cant remember the oil weights right off for diesel motors.on gas burners its 10w30.

 

[flaboy?]

I agree with bigbull. Rotella for the diesel. There are others but this one is good and can be found almost everywhere. Basically any oil that meets CH-4 API rating will be good for a diesel. Will other oils work? Sure they will but we really don't know what if any effect on the internals they might have over a long period of time so why risk it. Use diesel oil in a diesel and gasoline oil in a gas motor.

Oil weights could be discussed forever. Much depends on your climate. When all else fails go by the manufacturers recommendations.

I use 10W-40 in both my diesels and gas motors but they are two different types of oils.

I use straight 50W in my bikes.

 

[Dusty Britches]

what about a heavy oil like 5W-15?

 

[flaboy?]

what about a heavy oil like 5W-15?

5W-15 is a light oil, not heavy. Sounds like stuff they might use in the frozen north. I have been in Texas though when it was frozen over too.

I think some of the new V8 gas motors are actually being specified to use the 5W-15. I wouldn't use it in the summer for sure. The new Mustang motor recommends 5W-15 but I use 10W-40 in it with no problems. Then again it gets hot here as I know it does in Texas also.

 

[Dusty Britches]

Oh, my bad. sorry.

Let me just come out with "the story".

My sister has a 1/2 ton gas truck and her husband has a 3/4 ton diesel truck - same make. They change the oil on both trucks every 5000 miles, but her husband uses some sort of heavy oil in his truck and uses the same oil in her truck.

She has 120,000 miles on it and the valve spring broke. The push rod is bent. And the mechanic thinks the cylinder is cracked. No one knows what broke first.

Our theory is that the oil is too thick for the gas truck and caused premature wear on the engine.

 

[3MR]

You cant really compare gas and deisel engines like that. Thats like comparing a healthy horse to a sick cow expecting answers becasue they are on the same farm.

 

[DiamondSCattleCo]

Most diesel engines ask for a 10w40 or 15w40 dino oil as the "basic" oil to be used in summer conditions. I've never seen a gas engine truck that spec'ed a w40 weight oil for summer use, and certainly not one that spec'ed a dino w40 weight in the winter. I won't even use dino w40 weight in my diesel truck in the winter (bearing in mind that I live in the frigid north).

So long story short: Yes, the heavier oil could have damaged the gas engine.

As an aside, I'm a synthetic freak. I run 0w40 year round in my diesels and a 5w30 in my gas engines.

Rod

 

[flaboy?]

She has 120,000 miles on it and the valve spring broke. The push rod is bent. And the mechanic thinks the cylinder is cracked. No one knows what broke first.

Our theory is that the oil is too thick for the gas truck and caused premature wear on the engine.

Now this might start some "stuff" but.........usually broken valve springs and/or valve stems are not due to lack of lubrication. Valve springs fail mainly from fatigue, and push rods break for the same reason. Neither are oiled like a bearing. With that said, oil is also used as a coolant for these metal parts. A guy I went to school with used to work on some NASCAR teams. At one time as the head mechanic on one. We had this discussion and he told me they have never been able to relate a broken valve or valve spring to oil as a cause.

Now, could it be that the oil he used in his diesel truck did not meet the API requirements for the gas motor? If it did then my bet would be the "heavy oil" did NOT cause this problem.

 

[DiamondSCattleCo]

Good post, flaboy, and I have no idea where the poster is from, but too heavy an oil, combined with cold weather will equal no lubrication. Now, as you say, this will generally not equate to bent push rods or broken valve springs, but it is possible.

Rod

 

[tom4018]

In a fleet we ran 15w-40 in all engines, gas and diesel. Both types we put hundreds of thousands of miles on them with no problems. Even ran it in our service truck air compressor. We had gas engines with 250,00 or more than did not use oil in between changes and had run 15w-40 since the first change.

I do like the 5w-40 syn. rotella for the improved cold start. Out fleet trucks were usually in a warehouse so the cold start was not a problem.

 

[kjones]

So now I'm interested in what oil he was putting in those motors. I have worked in industrial lubrication for ten years up until last september. I also serviced a few pieces of equiptment as part of the job. I think it is highly unlikely that the dammage was caused by the oil. I was using the same oil in large diesel engines as in the pickup trucks and fork lifts. The supplier changed a few times over the years, but the viscosity stayed the same, 15w40 motor oil. All of these trucks were high milage trucks, that had been used very hard in the woods by timber crews. I think there may be something else as a cause, with three things breaking. If the oil was too thick there should be some sign of that in other places as well. Ask about the bearings on the mains and rods.

 

[shorty]

I use Shell Rotella 15-40W in all my gas and diesel motors.

 

[Dusty Britches]

Thanks, y'all. So our theory is incorrect. I appreciate the information.

 

[Stocker Steve]

In a fleet we ran 15w-40 in all engines, gas and diesel. Both types we put hundreds of thousands of miles on them with no problems. Even ran it in our service truck air compressor. We had gas engines with 250,00 or more than did not use oil in between changes and had run 15w-40 since the first change.

Diesel oil has a different detergent. Newer gas engines recommend light oil to maximize fuel economy. Nothing wrong with going a little heavy as long as you are not doing cold weather starts.

 

[KenB]

I use Shell Rotella 15-40W in all my gas and diesel motors.

I do also, I even use it in my Kohler powered gas lawn mower.

 

[cowwrangler]

i have used 15-40 in everything for years,tractor,trucks,pickup,have never had an engine go bad,all were high milage also pulling trailers

 

[MillIronQH]

I know several people that run Mystik JT-8 10-40 in everything. Cars, trucks, tractors, gas and diesel and swear by it.Z

 

[sidney411]

Is it true that once you start using a heavy weight oil you shouldn't go back to a light weight oil or you might get leaks?

 

[kjones]

Changing the oil viscosity won't cause leaks. In some circumstances a heavier oil might hide a leak that would otherwise show up with a lighter oil.