Anyone run 5 30 synthetic or 5 40 synthetic

I'm doing an oil change. I called Freightliner. For a 2014 dd15. They said 10 30 or 15 40. Anything after 2016 10w 30. But at Wally world. I saw the 5 40 and 5 30 rotella synthetic. Read the bottle claims better fuel mileage. I just wonder if it's too thin.

 

15/40 is what most use

 

Rotella T6 5w40 50,000 miles oil change intervals.

 

Yup, same here. Rotella T-6 5W40 Synthetic. I change mine every 500 hrs, roughly 17,000 miles. Severe service maintenance schedule. I do oil analysis every time.
2016 Cascadia DD16

 

What year and engine is your truck?

 

The first number (5,10,15) is the cold temperature flow point. It just makes it easier to start the truck in the winter. Which is a good thing.
The second number (30,40) is how thick the oil is at operating temperature. Both the synthetic and regular oils have the same number there. So you’re good to go.
Detroit Diesel Approved Oils List
T6 was approved in DFS93K222 & 223.Lubricants / Fuels / Coolants

 

I posted a comment related to this issue about a week ago. My 2014 Freightliner Cascadia has been using 10w30, which is what the Road Rescue department of Stevens Transport told me. I bought my truck from them. However, recently I just wanted to double check this. My Detroit engine manual says 10w30 for fuel efficiency, but that other engine oil types can be used.

 

My rationale for doing my own fuel filter and oil changes is not exactly to save money, although initially that was my goal. It turns out that you won’t save much, especially if you have a modern truck with oil change intervals over 30k. If you don’t idle your truck, you don’t drive 70+ mph every day, and you do long haul, then you should be fine with what your engine manual has listed for highest oil change interval. On the DD15, that is 50k. Newer trucks are probably 60k or higher. Again, meeting the criteria I just listed above. If you are unsure, you can send your used engine oil to the lab for analysis, and so it can help you decide the best time and/or mileage for oil changes on your truck.

The reason I now do my own PMs is to ensure it is done right every single time. I’ve wasted time in the past with mechanics breaking filter caps and even refusing to do an oil change because the drain plug was overtightened. A lot of these mechanics are doing these PMs in a hurry, so it’s possible they don’t torque to spec, or worse, that they accidentally forget to replace a filter. It can happen. Then there are the times when they don’t grease the whole truck.

 

Absolutely true. My last truck, at first I let the dealer do the PM's. But i found they were missing grease zerks. One spring hanger grease zerk was stuck, when I changed it and pumped in fresh grease, a bunch of rust came out.
After that I always do it myself.

 

2013 DD13, any modern engine in good condition should be able to do 50k intervals backed up with oil analysis.