another ?

[matt hurtado]

my 92' sounds like a deisel when idleing .will thicker oil help and is this a characteristic of this year or something or am i in store for a dead motor in the near future

[Matthew Currie]

A lot of 4.0's of that vintage have noticeable piston slap. If this is what you're hearing, thicker oil won't help and the engine will probably last forever anyway. But you should check carefully to make sure that other things aren't lurking underneath the basic piston slap.

A bad timing chain, a bad pulley or water pump, for example, can sound similar, and blend in with the slap sound.

If your lifters are noisy, thicker oil probably won't help very much either, but a couple of unusually short-spaced oil changes with premium oil might.