Moly vs. Cast Iron Rings

[tom99xj]

I'm doing my first rebuild and I'd like to get some feedback on my build. My 99 XJ is stock, 4.0 I6. It has 300,000 miles and it sees mostly around town and freeway miles. My goal is to restore in to stock specifications. Before I visit the machine shop, I'd like to get feedback on this piston and ring combination:

Silv-O-Lite Hypereutectic Pistons 3241HC.030
Mahle 51870CP.030 Piston Ring Set

These rings are cast iron, but I have read a lot about moly rings. Are there significant advantages to running moly rings, or should keep it simple and run cast iron rings? Thanks for the help.

[mpgMike]

Moly are the way to go. Cast iron will tear up the cylinders and wear out quickly (think 1960's engines). There is another option -- chrome. DON'T USE CHROME!! My current 4.6 stroker was built with the higher-priced optional chrome rings and it is still using way too much oil after 2200 miles. Go with the Moly, that's what your 4.0 originally came with.

[tom99xj]

Moly are the way to go. Cast iron will tear up the cylinders and wear out quickly (think 1960's engines). There is another option -- chrome. DON'T USE CHROME!! My current 4.6 stroker was built with the higher-priced optional chrome rings and it is still using way too much oil after 2200 miles. Go with the Moly, that's what your 4.0 originally came with.

Yes, it seems Moly is the way to go. I visited three machine shops this week for quotes, and hands down, everyone recommended moly rings. Thanks for the vote. Moly it is.