Why not 5/40 Synthetic over 100 degrees?

[Mr. D]

Why not 5/40 Synthetic over 100 degrees?

Wouldn't a 5/40 be the same viscosity as 15/40 at high temps? Isn't that what the 40 means? So what do you think about using 5/40 synthetic since GM says it is not approved above 100 degrees? What sense does that make unless GM doesn't trust the 40 weight in the 5/40?

I though 40 weight was 40 weight!

[More Power]

There was a rumor about 3 years ago that suggested GM/DMAX was considering using Mobil Delvac 1 5W-40 as a factory fill in the Duramax. GM uses Mobil syn in other engines as a factory fill - i.e. Corvette.

Jim

[Mr. D]

There was a rumor about 3 years ago that suggested GM/DMAX was considering using Mobil Delvac 1 5W-40 as a factory fill in the Duramax. GM uses Mobil syn in other engines as a factory fill - i.e. Corvette.

Jim

When they elmiminate underhood lights and go to Dino oil in the Allison from a 50/50 Transynd blend, I suspect they would rather not put 10 qts. of synthetic in the engine as a cost saver! It all adds up!

Does Mobil Delvac 1 5W-40 come as a diesel rated oil? Hard to find in my neck of the woods! (Or desert)

[Tough Guy]

When they elmiminate underhood lights and go to Dino oil in the Allison from a 50/50 Transynd blend, I suspect they would rather not put 10 qts. of synthetic in the engine as a cost saver! It all adds up!

Does Mobil Delvac 1 5W-40 come as a diesel rated oil? Hard to find in my neck of the woods! (Or desert)

If you live near a Wal-Mart (don't tell 16g SxS) buy some Rotella T 5w-40 synthetic there...its good stuff and is aroud $14 for a gallon. The same basic properties as the Mobil Delvac 1 5w-40....just less expensive.

Chris

[Mr. D]

Shh-hh, not so loud Tough Guy! I already did! $14.38 a gallon plus tax, license and dealer prep!

[Tsckey]

Mobil Delvac 1 IS the diesel rated oil, but much harder to find. Mobil 1 Truck and SUV oil is essentially the same, but not identical. It's also easier to get. My first UOA after switching from Delvac 1 to Mobil 1 T&S oil was virtually the same. Just because I

[oyazi]

FWIW the T & S isn't CI-4PLUS rated whereas the newer/replacing diesel truck supposedly is.

[jbplock]

FWIW the T & S isn't CI-4PLUS rated whereas the newer/replacing diesel truck supposedly is.

Has any one seen the new M1 Turbo Diesel Truck 5w40 on retail shelves? None around here yet .. (upstate NY)..

[Mr. D]

Has any one seen the new M1 Turbo Diesel Truck 5w40 on retail shelves? None around here yet .. (upstate NY)..

I can't find it in California either, but I live in the High Desert and I can't find a lot of things! Many stores don't sell enough of it to bother stocking it! I gave up looking and bought some Shell/Rotella T 5/40 Synthetic at Walmart!

[SoTxPollock]

Hey MR. D , your right 40 is 40. Its only in the lighter end (colder that would or should be different between 5W and 15W. You gotta remember the guys that print those little pictures of temperture vs viscosity in the operators manuals have to show general conditions and GM's recommendations for such. I wouldn't worry too much about viscosity, its just an ASTM test of how a liquid pours through a certain size hole at a certain temperature, in other words how it flows and how its flow varies with temperature.
Since the number doesn't go above 40 on either the 5 or 15 it means nothing above 100 degrees outside temperature if you start with the 5 or the 15. The thicker the oil the harder it is to pump through the openings thus increased fuel costs in cold climates. I personally will always run 5W-40 so I can limit my stock of oil to one type.

[16gaSxS]

If you live near a Wal-Mart (don't tell 16g SxS) buy some Rotella T 5w-40 synthetic there...its good stuff and is aroud $14 for a gallon. The same basic properties as the Mobil Delvac 1 5w-40....just less expensive.

Chris

Hey Chris......I use the same stuff from Wally World......Just don't bring your truck in for a oil change and tell them about the firearms you have in it, or the dogs in the back.

[Tough Guy]

Hey Chris......I use the same stuff from Wally World......Just don't bring your truck in for a oil change and tell them about the firearms you have in it, or the dogs in the back.

It'll be a cold day in he!! before the flunkies at Wal-Mart change my oil....

I was just having a little fun at your expense!

Chris

[Driveshaft]

The 2 fairly local Walmarts around me have quit stocking the T&SUV 5W40. Said they didn't get enough call for it. Guess I will have to go back to my local Delvac dealer for $20 a gallon. Bought the last 25 qtrs from one of the Wally worlds for $102.

[Driveshaft]

Could somebody tell me how to jump straight to the new posts? Thanks, in advance.

[DmaxMaverick]

Could somebody tell me how to jump straight to the new posts? Thanks, in advance.

Change the setting in your user profile. There are other options, but your request isn't specific. When you open a forum, a thread with new posts should be bold, and will have an icon (square with a chevron) next to the thread title. If you click on the icon, it'll take you to the newest post in that thread.

[Driveshaft]

Thanks. When I came back today, it was clear how to go to the newest post or 1st unread post.

[silverback]

Here's the link from Mobil on the new Turbo diesel oil. It is CI-4 rated. I'm going to order some from AV Lubricants today (comes to about $6.35 a qt.). And I've been using synthetic 5W-40 for two Arizona summers now.
-KL