monitor your engine oil level to verify that it is in fact an engine oil leak. If it is, 9 times out of 10 it is the rear cam plugs. I have a 97 SR and 97 LS and my dad and brother both have 99 monteros (same engine) and all 4 of them had bad engine oil leaks right around 70-100k miles. in all 4 monteros, replacing the rear cam plugs stopped the leak. the plugs are cheap, but labor is pain in the <img src="/forums/images/graemlins/butwiggle.gif" alt="" />

97 Montero SR w/Mitsu Adj Shocks & Rear Diff Lock ARB Front Diff Lock 4.9 Ring/Pinion 3.15 transfer box 43:1 crawl ratio 2" suspen lift 2" body lift 2" Gas Tank Lift 35x12.5 MTRs 15x10 Wheels Rock Sliderz ARB front bumper w/12k winch Custom rear bumper