My truck has about 150,000 miles on it. I have had it for about the last 20,000. I have used regular 15w-40 on my oil changes. As for the first 130,000 im sure they used regular oil as well. I hear all of these great things about synthetic oil, but i have my doubts. I have heard of people with high miles on their trucks that have switched to synthetic and end up with leaks because of the detergents breaking down deposits that have kept the leaks hidden. I guess my question is would it be worth it to switch to synthetic or stick with what has been working for me?

 

You can do a search on Oil threads and stay busy reading for DAYS with a 1000 different opinions.

My suggestion is to stick with what your doing. If it isn't broke...don't fix it. Many trucks have gone a million miles with good ole dino oil.

 

I've swapped several high mileage vehicles over to syn.with no issues.In fact been reading these Dodge diesel forums for a long time from 1st eneration on up and have never read about a leak caused by changing over to synthetic.Maybe some gas engines with lots of deposits and compromised seals but never on these Cummins.In fact I've swapped gassers with 80k plus over to full synthetic with no issues.

 

trod, read this.

By the way, are you planning on going with extended drains? If not, then a syn oil is a waste of money. Slap some Delo in your engine and be done with it.

 

At present i change the oil and filter every 5,000 miles. What kind of change interval could i expect with synthetic? I know that it is more expensive and i can go longer between changes, but is there any real mechanical benefit to running full synthetic oil?

 

I doubled the drain intervals with Amsoil synthetics.Actualy on my gassers I go more then double.My 03 3500 gets a oil and filter once a year which so far has been only 5k to 8k.Lots of differant ways to use group 5 synthics and not spend much if any more then using a good dino oil.My 3500 is due in Feb.for a oil and filter and its been about 6k.It has Amsoil 15w40 syn.in it.

 

Schaeffers 9000, 5 bucks a quart. 1st synthetic at 20,000. The motor is quieter and smoother running.

 

You can EASILY run a synthetic out to 10K.....I stress the word easily. Realistically, with a high TBN syn oil you can expect at least 15K barring no outside contamination. Don't expect lower wear numbers with syn oil, but expect better heat resistance (useful in turbo applications), and a base stock/detergent package that keeps the engine cleaner especially when a syn oil is used throughout the life of a vehicle. That's just a few advantages to mull over.

IMO, with a high quality dino oil you can also expect 10K change intervals easily.

 

i dont use synthetic oil unless the application calls for it. for example, i run regular rottella oil in my truck because it is a daily driven work truck and doesnt see "alot" of drag racing or any extreme conditions such as sled pulling or rock crawling. i ran mobile 1 synthetic in my race car because it was just that, a "race" car. the motor was under constant abuse, constant high rpm (10k rpm), constant high temps all of which definately are not "everyday normal driving conditions". an abusive application benifits from synthetic oil, a daily driven application does not. this is why i do not agree w/ all the overthinking that everyone puts into which oil to run in their daily driver. not to mention the $$ difference people waste running synthetics when they arent needed. you cant go wrong w/ any good quality name brand "regular" oil, save the synthetics for when they are actually NEEDED.

 

Thanks for the info. I'll probably just stick with the dino oil since it doesnt look like there is any major advantage to offset the price.