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

[Wolfy]

Any members try this? Right now, I have to keep on hand: 5W40, 15W40, 10W30, 30W, and 5W30, in both regular and synthetic. A, It is getting tiresome stocking and tracking all of these weights. And B, the 5W40 would allow the engines to start bettter in the winters around me that seem to get colder every year. Upon research, I am convinced 5W40 would be great in my vintage air cooled engines. The only road block for me, from entirely switching, is my 2006 Ford F350 that I run 5W30 synthetic in. But if that could use it, I think I would change over everything. Shell Rotella, Mobil One, and Delo 5W40 synthetic are all stocked in most stores around me, so availability is not an issue.

 

[sixdogs]

I ran that in a gas truck six cylinder engine and I have LOTS of oil pressure. Too much, if that's possible. I'm going to switch it out before winter since truck rarely gets used. The high pressure bothers me. So does lower oil pressure so maybe it's just me.

 

[DK35vince]

I keep 5w-30 oil for the cars and truck..
and Rotella T6 synthetic 5w-40 goes in the tractor, zero turn, ATV, motorcycle, push mowers, generator, water pumps, Etc.

 

[KubotaToy]

I have been running it in all things with an engine for several years now (except my Victory motorcycle), the only thing that bothers me is the price..

 

[davesl708]

I was in the same boat as to having so many different oils. I switched my car, SUV and BX to Rotella T6 5w 40. The car used 5w 30, the SUV and tractor used 10w 30. The car used oil (1qt.per 2000 miles). After switching the car stopped the oil loss and ran smoother and quieter. The tractor is quieter as well.
The SUV hasn't had any change.

 

[Gary Fowler]

I used to be in the same boat with lots of different oils on the shelf. Now I use Rotella T5 10W-40 in everything from lawnmowers, cars, truck, motorcycles and tractors. I haven't had any issues with the wet clutch on my Goldwing Honda while using the T6.

 

[DEWFPO]

I use synthetic 5W-40 in everything. Have for years. We have cold winters and hot summers. Never had a problem.

DEWFPO

 

[KennyG]

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.

 

[LD1]

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

 

[davesl708]

T6 is API rated SN for gas engines. I have had better results with T6 5w 40 in my Subaru and Kubota.