Fuel economy heavy duty diesel oil

No intension to Hi Jack this post here but I am alsovery interested in hearing about real world experience vs the theory here. We know engine oil has 2 main functions.(1) Keeping moving surfaces apart so they don't rub up against each other and wear or damage each other. (2) Cooling components by absorbing the heat from the component then transferring it to the cooler.
Pumping a thick (viscous) fluid absorbs more power and transfers heat slower than thinner oils.Both of these are properties are undesirable. Traditionally viscosity has been directly proportional to the film strength/sheer point of the oil film keeping the moving parts apart. We are now told that these new oils have the advantages of thin oil for fuel consumption and cooling with equal film strength/sheer point to thicker oils.

(1)Is extra cost off set by the claimed fuel saving?
(2)Is there really no compromise to component protection?
(3) Over what period / miles covered are your opinions based?

 

I have wondered about that as well, but haven't tried anything besides 15W-40.

If one of the mods would move this thread to the garage section, it would probably get a lot more replies.

 

I have tried a 5w30 synthetic in my smaller diesels and have had decent results. Haven't tried it in my ISX. I just use a 15w40 synthetic blend in that one. Mostly because I can get it at a price that rivals or is below the standard oils.

I really can't see how using a 5w30 or similar in a diesel would be that bad. From what I understand, Amsoil has had a carrier out of Superior, WI (or Duluth, MN) using their 5w30 synthetic in the entire fleet of trucks. Oh... I think that carrier is Jeff Foster. From what I have read, they seem to be doing fine on it. One might try to get ahold of their maintenance supervisor and ask some questions.

For me, I would prefer giving it a try in a newer engine. One that has a lot of miles might not work as well as one would hope... maybe too thin for a well worn engine. But if I had a new engine or a recently rebuilt one, I would give it a try. When I do a rebuild on mine, I might just do that. I can get a 5w30 synthetic blend from my oil supplier now for around $10 a gallon delivered. I get their 15w40 synthetic blend for $9 a gallon delivered. They have been wanting me to try their 5w30.

 

After I break-in my 3406 in the coming weeks I'm going to switch from Delvac to Amsoil 5W40 synthetic...

Delvac (and Pennzoil Long Life) have served me well the last 12 years or so but it's time I went back to synthetics. i used AMSOIL 15W40 back in the late 70's/early 80's and it was very good... got lots of miles on one engine in particular.

Also going to install the bypass filter that I bought years ago but never used.

 

I believe 5W40 synthetics are approved by most engine manufacturers. 10W30's are Ok with everybody unless your ambient temps are above 90F I believe.

AMSOIL makes several different engine oils... more info can be found at www.amsoil.com .

 

I would agree with Krooser. Most of the OEM's are ok with more recent engines using a lighter synthetic oil. One thing about all this, a 5w30, and especially a 10w30, will shear less, generally, than a 5w40. That is a plus. Overall, it should maintain its viscosity rating a little better than the Xw40 oils.

I am a big fan of synthetics, but cost factors into the equation as well. I use the full synthetics a lot in my smaller diesels that don't operate as much. But for my ISX, I settled on a 40% synthetic blend from my oil supplier that I can get, delivered to my door, for $9 a gallon. It might pay for you to shop around to various oil suppliers and do some pricing before you decide. Amsoil is a good product, and I use it in some applications. Pricing is not their strong suit. Same can be said for the Mobil synthetics. You should be able to find a good quality 10w30 synthetic or blend at better pricing than even Wally World, from a local supplier. Same is true if you decide to stick with a more traditional grade of oil.

 

http://www.schaefferoil.com/supreme_9000.html