Looks like I could run 10W30 for most of the winter around "here". I just did my first OC at 2600 miles to Delvac 1300. Thinking 10w30 might make for easier starting and faster warmups. Winter weather is usually in the 20-30's. Might see zero once or twice a winter.

Seems like the 30w wouldn't be up to the task. 15w40 in the summer, 5w40 in the winter.


JP

Just make sure the 10w-30 youv'e found is actually diesel oil.

I would stick with the 5w to 15W 40 oils in our trucks.


Bob

Pick said "Thinking 10w30 might make for easier starting and faster warmups."


Sorry to be crude but from my personal experiences this is what I think: No matter what kind of oil you run it's not going make any difference in the way your truck starts, and no significant difference in how fast it warms up. Want to see results plug in your block heater.

Switch to Delvac I 5w 40 ,then report back on "cold" morning start-ups ....

Mac http://www.dieselplace.com/forum/smileys/Wink.gif Edited by: Mackin

I ran Amsoil Series 3000 5w-30 Synthetic HDD oil for a couple of changes. I did not like how my analysis looked with it so I switched over to Mobil Delvac-1 and haven't looked back since.

From what i've heard the Amsoil Series 3000 5w-30 is not good diesel oil to use.. However their 15W-40 HDD & Marine is great.. Not sure why they sell the 3000 since the original stuff is way better...

I switched to Shell Rotell Synthetic 5W-40. It's at Wal-Mart for around $13.00 a gallon.

Last 3 or 4 times I've been to Wally's, I haven't seen any Shell Rotella Syn 5w40. I'm beginning to wonder if at the less that $13 a gallon price they were discontinuing it.

The Duramax owners manual specifies either 5W-40 or 15W-40 with a CH-4, CI-4 rating. …I'm not an oil expert but if I understand the oil specification correctly, the W numbers (5 or 15) are a measure of the oil's low temperature performance (lower number oil will flow better at low temps) and the second number (i.e. 40) is a measure of the oil's viscosity at operating temps (100degC). Since the Duramax is designed to run with an oil that is "40 weight" when it's hot, I would think it unwise to use any of the "X-W30" oils (0W30, 5W30, 10W30). IIRC, the 40-weight rating is a factor in how the oil protects the crank bearings under load. http://www.dieselplace.com/forum/smileys/Geek.gif

I agree with the rest. Get yourself some synthetic 5W-40 if you need the protection. Last few times at Wal-Mart I could not fine the Shell synthetic on the shelf let alone a price sticker in an empty space.





About 2 months ago at Wal-Mart, I bought every gallon they had in stock at $12.88.

Jbplock....My '03 suppliment for the DMAX shows that 10w30 can be used from 0-100 degrees F. Does yours not show that? (I'm not saying it should be used, but the suppliment shows it to be acceptable).

Jbplock....My '03 suppliment for the DMAX shows that 10w30 can be used from 0-100 degrees F. Does yours not show that?





Roegs,


Thanks for pointing this out! http://www.dieselplace.com/forum/smileys/Embarrased.gifI stand corrected.http://www.dieselplace.com/forum/smileys/Embarrased.gif I checked my 03 Diesel supplement and it does say that SAE 10w-30 - with a CH-4/CI-4 rating - can be used for ambient temps from 0 to 100 deg F. It also states that 5W-40 should be used when temps are below 0 deg F. However, I also checked my 03 Helms manual and it says to use 10w-30 for temps BELOW 32 deg F with no mention of 5w-40 (??)http://www.dieselplace.com/forum/smileys/Confused.gif. The Helms also says SAE 30 is acceptable for temps above 32 deg F… And… Both the 03 diesel supplement and the Helms state that 15w-40 is preferred for temps above 0 deg F and NOT to use 10w40 or 20w50…


Hmmm…. I think I’ll stick with 5w40 synthetic – good for both temp extremes…http://www.dieselplace.com/forum/smileys/Geek.gif