I had a guy that worked for me change the oil in a 99 5.4 ford and he put in Rotella 15-40 the truck locked up tighter than a tick less than 10 miles down the road. The clearances in the ford modular motors is very tight and thicker oil was unable to lube it IMO.

 

The motor locked up so hard and fast it broke the new trans at the same time.

 

You had other issues then the oil weight to lock up like that.

 

I was told that the mains on these fords are very tight and not using the correct oil will not allow for lubrication.

 

40 weight oil is not thick enough to lock up anything. Something else was wrong.
Many small car and truck engines are rated for 40 weight oil and some prescribe it for use. Case and point VW's 1.8 liter turbo gas engine.

 

My Toyota PU has over 300k and Honda Accord almost 200k on Delo 15-40 since they were new. Except for the typical fuel pumps, water pumps alternator, starters, etc the interior of the engines have never been touched. Neither uses any oil.
Since I buy my Delo in 55 gallon drums I see no reason to stock other types of oil.

 

I also post on some performance boat forums and many guys there use diesel oil in their high performance boats - especially for break in. If it is good enough for a 1000HP big block it should be good for anything. I am not quite sure why they use it, but they do.

 

On the newer vehicles, thicker than specified oils can indeed kill the engine fast.

They have the tolerances tightened up to the point that 40 weight can not flow enough to remove the heat.

Oil pressure is only a small part of the equation, if enough volume does not flow across the bearings, it cannot remove enough heat, and engine gets toasted.

Read the manual and follow the recommendations.

 

they probably use it to get the rings seated, lotsa horses usually is followed by lotsa compression. depending on the way the hp is created of course.

 

Delo is universal rated- you can use it in either gas or diesel engine.


For sluging- best I can tell it's from extend oil changes based on synthetic oil with regular oil. If mileage is not too high- I would run Mobil-1 and change it every 3 k miles for several times. I think this was Merecedes factory cure for FSS cars which ran dino..

Michael

 

I have run shell rotella synthetic 5w40 in all my gas vehicles for years, I love that stuff. I think that 15w40 regular rotella is a lot thicker and I dont think its a good idea in a tight newer gas car engine.

 

A 40 wt oil is a 40 wt oil...... synthetic or mineral oil based! Same thickness (at 100*C). If anything, the non synthetic will thin out faster, should the oil temps get hot (over 100*C or 212*F).
Lots of misconceptions out there about synthetics. Fact - The only REAL advantage of a synthetic oil is 'Thermal Stability'. (but it's a big advantage). A synthetic, say a 15w-40, will stay at rated viscosity well above 100*C and will stay like a 15 wt well below 0* C. This stability prevents molecular shearing and keeps the oil from breaking down....reducing the sludge factor and allowing longer change intervals.

I agree a 15w-40 should not be used in vehicles calling for 5w-20 wt oil! May run for many miles but you will increase wear and shorten the life of the engine. Using a 15w-40 diesel oil in a car calling for a 30 wt. has produced no problems I'm aware of.

RJ

 

Good post from RowJ.

I'll add this: viscosity and film strength are not the same thing. Certain grades of synthetic can offer you higher film strength at the same viscosity, or lower viscosity at the same film strength.

So it's possible that in some cases, a 30wt synthetic might offer protection equivalent to a 40wt petroleum (group1) oil. Comparing HTHS and other measures of oil performance validates this. So you can get the superior startup flow and heat reduction of a thinner 30wt oil and not give up the shear protection (valvetrain) of a thicker oil.

I thought Redline 10w-30 worked VERY well in my truck, but that's just speculation (no UOA) and I could be totally mistaken.

jmo