New oil as flush pre new-fill.

[Jeff_in_VABch]

A jeep 4L doesn't need a flush or anything done to it but driven until it totally [censored] out.

At 200K that thing is probably making all kinds of clacking, ticking and clicking. That is just the way they are. It probably has a lot of miles left in it.

If you want to clean it, take out that engine and put a newer one in. Its a waste of time to tinker with it.

 

[IllinoisSparky]

Originally Posted By: UltrafanUK

If you want to use a flush additive it's safer to use one designed for use at idle only. Both Liqui Moly and Amsoil make good idle use flush additives for use just before an oil and filter change. The engine only needs to idle for 10 or 15 mins, so even if the filter blocked they won't cause any real damage.


+1

I have used the Amsoil Powerflush on my Ford, and will use the LM flush on an old MB this summer.