I searched but could not find a thread on using diesel oil in a 460 engine. I don't want to get a debate started about which oil is better, only if it would be beneficial to run diesel spec oil like Rotela T6 in a gas 460.

I hear some people run 20-50, or 10W-40 in winter. While looking at a forum dedicated to oil, "bobistheoilguy.com" I see people using the newer turbo diesel in their large v8 modern gas engines.

Since diesels have compression rations of around 19-20:1, I am led to believe that diesel oil has a higher sheer strength. Since the newer diesel oil has a 5W-40 weight I am wondering if this is a good fit. Good flow without loosing shear strength.

Any thoughts?

Thanks ~C

 

Well, for a short period, people were using the diesel oil because of the higher ZDDP content, but that has been reduced now as well. IMHO, just run the correct weight of oil you normally would, and add a can of ZDDP which is available from any performance shop, cam mfg, etc.

 

Is the ZZDP what gives oil it's shear strength?

~C

 

There are a number of factors to consider in this. I would suggest you first read up on oil sampling and analysis programs.
If you are not familiar with such programs, oil analysis is used to measure the remaining additives and any contaminants in the oil to get an idea of overall engine health and determine the next or best oil change interval. I recommend Blackstone Labs, as they are the ones I use to check the quality and extendability of the oil in my 7.3 F-250 Power Stroke diesel. They have some good write-ups about all of this on their website.
Look for terms such as TBN and TAN, probably the two most important.
The primary difference between regular and so-called "diesel" oils is the additives, which tend to be higher for diesel use. The starting numbers for "car" oil use tend to be around 6, whereas those for diesel applications are about 14 - hence the higher cost. Additives get used up or deteriorate over the life of an oil's use. Most car drivers are not interested in spending the $35 for an oil analysis, it is cheaper and more efficient to just change the oil every 3K - 5K miles.
However, with a diesel oil change running upwards of $3500 (for static generators), a $35 analysis will save a huge chunk of change.
My F-250 costs $125 with filters. Oil analysis has pushed the miles I can run from 5K miles to 7500 miles, and possibly up to 10K, depending on the next sampling. So you can see I have saved an oil change and paid for the analyses in 3 oil changes.
By the way, oil analysis will tell you how much, if any, iron, aluminum, fuel, coolant and more is in your oil, which gives you a good indicator of the engine's health.
I realize this has veered off a bit from your question about shear specifications, but there is much more to consider. An examination of oil analysis programs may give you the answers you need.

Good luck!

 

ZDDP is an anti wear/scuff additive that constantly replenishes itself on metal surfaces.
It is recommended for hydraulic cam break in and solid lifter engines.

FWIW, after losing my engine to a cold weather startup in 2008 I have been running Rotella T6 synthetic 5W40 (gallons on sale at Walmart) for the past two winters without any apparent ill effects.
Pressure is good and it definitely reaches the sender faster than 10 or 15 weight.

No endorsement or claims, just my personal experience with this product....

 

Thanks for the info.

I am familiar with Oil Analysis in an industrial hydraulic setting.
The reason I ask is about diesel oil is some believe that diesel oil has a "better" additive package that my protect the engine better. I know it is rare to have engine failure from oil as long as it is changed when needed, and correct type etc. I'm not looking for extended drain intervals. 5k max.

The oil types the 460 van lists in the owners manual for gasoline engines is:

5W-30 (below 60 deg F)
10W030 (above 0 deg F) "Preferred"
15W-40 (above 10 deg F)

Seems like they forgot about 10W-40, which I put in at the last oil change since temps are coming up. Was running 5W-30 in the mountains of Colorado. Last few months have been unusually cold, (negative #'s)

My thought was that I could get the best of both worlds (winter-summer) running year round with a 5W-40 oil, which as far as I know is spec'ed for Diesel.

Owners manual specs 15W-40 witch as far as I can tel is a Heave Duty Diesel Oil.

This is my reasoning for asking about diesel oil.

The cargo van is used in a business, has a 9,600 GVWR and typically carries 2k-3K lbs in town driving.