I have a 02 dmax and have 109,000 miles on it. Have used mobil delvac 1300 15w-40 sence new. Can I switch to mobil 1 delvac 5w-40 syn. oil with no problems. or does my engine have to many miles on it.

I would stick with what you have been using if it's been working for you. You might spring a leak going to synthetic with that many miles, or burn oil -- others have had this problem.

If you don't have any leaks I would go for it. I haven't heard any real cases of causing you to burn more oil usually if you're burning oil you will see a decrease in oil consumption.

Got 180k on the bosses '02 on regular 'ol Kindal hd30, no biggie.

I don't see any reason to switch if what you're using is doing the job well. However, if you want to switch anyway I can't see any reason you couldn't switch. 100-150 K isn't high mileage for a diesel.

My truck was never happy with syn oil. It burned it and also lowered the oil pressure when hot.

My truck was never happy with syn oil. It burned it and also lowered the oil pressure when hot.

you mean to tell me a synthetic oil...produces a lower oil pressure when its hot...hmm go fiure...who would have thought that a thinner oil with more viscosity would build less pressure:banghead:

I've used synthetic oil for over 30 years and never had any of those problems, and that is in a variety of engines. Some engines had over 200K and never used oil, and I wouldn't have bought all that expensive oil if I hadn't had good results. Many high-end vehicles come from the factory with synthetic lubricants, and the only reason all don't is price. FYI high oil pressure in the winter usually means that the oil is bypassing the filter because it is too thick, and that is one big advantage of synthetics. Or, you can just disregard all evidence and stick to dino--its your truck.

you mean to tell me a synthetic oil...produces a lower oil pressure when its hot...hmm go fiure...who would have thought that a thinner oil with more viscosity would build less pressure:banghead:

Yeah and go figure when I thought 7lbs of oil pressure was a bad thing.
I had a whopping 32lbs at 2k rpm when hot.

And I put 560k on a stock grand am with dino oil. The engine was fine.

My old Saturn used to burn Mobil 1 when I used it but never burned a drop of Castrol Syntec. I've read many times that M1 is a better synthetic but like everyone is saying, every engine is different. If you are going to longer drain intervals, burning a little oil isn't a bad thing as your additive package keeps getting renewed. Check this out.

http://neptune.spacebears.com/cars/stories/oil-life.html