Oil question,?

I’m pushing 17k now. Detroit’s original 12.7 recommendations were 15k. I went 20k, for over 1 mil. on last inframe. It had a lot of leaks, blow by, and burned quite a bit. Used a lot of Lucas, last few yrs. Bull gear lasted 2.3 mil miles. Lucas maybe? It had some sludge in it though. Now no more Lucas, and planned on going back to 15k. Mainly to protect the rocker rollers. They’re original. Might swap them out in a couple yrs. for reman rockers. That’s the only thing missing in my overhaul, compared to Detroit’s step 3 full overhaul. $2100 for rockers. Mine were good. Oil cooler wasn’t changed either. It’s still good. Detroit makes you buy all that stuff, to cover themselves on the warranty. Made that mistake before. Doubles the price of an inframe. It’s overkill. Oils cheap, and much better now. Low sulfur diesel keeps it cleaner too. Like unleaded fuel in cars. Oil lasts longer, plugs don’t fowl out. Used to need new spark plugs every 10k, now it’s 100k+ easy. They don’t make them like they used to. Thank God.

 

Plugs got to 100k when HEI ignition rolled out.

They don't usually last that long though.

You won't go that far with today's ignition system. Recommendation is now 60k.

Smaller gap too.

 

I do 30k on my DD15’s and oil samples come back saying I could probably double OCI but 30k is good and I run DELVAC 15/40. No oil usage between changes. Less than 4% idle time
It comes down to what your comfortable doing and oil samples and mfg recommendations

 

Well, I use good old 15/40 in my 2020, 2018, 2019 DD15’s and no issues yet with oil samples or warranty

 

And you shouldn't have any trouble as engines built to be FA-4 compatible are also backwards compatible..

 

How do you mean you aren't getting an accurate reading on the stick? To low? To high or inconsistent?

Obviously flat is good. If leaning away from dipstick it will read low. If leaning towards it will be high

 

Next oil change try 15w-40. Or go back to to Delvac.