I just purchased a crate engine for my 2000 XJ. A cracked cylinder head, down time, and enough sludge to put Exxon-Valdez to shame is what deterred me from rebuilding my current engine.

That said, my engine arrived today, and as I was reading through the paperwork there are some big fat letters that read “It is HIGHLY recommended that a non-detergent oil be used FOR THE LIFE OF THE ENGINE”

They also go on to recommend a ZDDP additive for the flat tappets. Some of their logic seems a bit old fashioned with regard to this. I get that conventional oil is the way to go for break in. I understand that ZDDP is important for older style engine, but what I don’t understand is the non-detergent part.

What about a detergent oil is bad for an engine? From what I know about oil, all non-detergent does is lubricate, nothing else. So, wouldn’t you want an oil with a detergent package vest suited to your engine?

They argue that it’s an older engine from a different time, but truthfully other than a lack of zinc in modern oils, it seems to me that you would want more advanced tech to maintain your engine. My last engine was treated like crap for 265k miles. Never complained up until the bitter end. It didn’t even seem to mind the cracked head.

I’m not putting the manufacturer’s name in the thread because I don’t want this to devolve into some “should have bought an X”. And my local engine shop is 12 months behind, so they were off the table.

 

Non detergent oil, like the type used in air compressors won't keep the contaminants in suspension and those will end up in the bottom of the oil pan and any where else they settle out..How in this day and age a rebuilder recommended that oil compared to the modern engine oils out there is beyond me...Seems like they're setting you up for voiding the warranty if something goes wrong and you don't use that oil..Is there even such a thing as a non detergent oil as good as a normal engine oil ??

 

That’s what I figured too. I’m going to have a chat with one of their representatives today.

 

I'm on the fence about the need for zinc with our 4.0s. While I think about it though, I decided to run "driven" synthetic racing motor oil, which contains zinc (and other good ole stuff). They have a rather lengthy video on Youtube, that, among other things, explains how the detergents in oil prohibit the zinc from bonding with the bearings and actually cleans zinc from surfaces. I'm not sure I buy it all, my brother has a '94 XJ he has had since new that is about to turn 300k. He has never run zinc, but I'm not sure if he runs detergent or not - although it is getting harder to find non-detergent oil.

 

Ask if they've found a history of leaky seals on the engines where detergent oil was used (just did a job where O-rings were completely destroyed even though recommended lubricant was being used. Problem was the composition of the O-rings).

Perhaps RMS etc. seals are of inferior quality, and detergents will eat 'em up.

 

Non detergent oil is basically a normal break in oil. I would recommend using it for break in only. Use it for a 1000 miles with a zinc additive, then dump it and run whatever oil you want.

 

There are thousands of people on this site who have run their motors for the past 20+ years on off the shelf, dino and synthetic oil. Both of mine made over 250k on regular oil...with that said. What is the warranty on your new motor?

 

for what it is worth, Valvoline Full Synthetic High Mileage 10w30 contains 820 ppm of Zinc.

 

Here's a shot of mine when I was changing the oil pan gasket.. Nothing but Penzoil 10-30 for the life of the vehicle...Doesn't get any better... And it will continue to get the same until it's dead...