I have a 2004 G35 Sedan that for the past few months I've noticed a slow leak behind the oil filter. I've taken it to a shop that had it up on a rack for half a day and they said they couldn't locate any leak but I just went on vacation and after about 2 weeks when I returned I found that it was a little over a quart low. I'm worried that it's the RMS. Has anyone had RMS leak problems with these engines? I'm not sure about the cost to repair. I'm wondering if I should get it fixed or clean it up and trade it in at a dealer. I'd prefer to keep it if the cost to fix isn't prohibitive.

 

If you had a rear main seal leak the leak would be by where the transmission meets the engine. If you have a leak behind the oil filter i would look at the seal for the oil cooler sandwich that comes from the factory or the oil filter seal itself.

 

^^This. When I bought my car at 46K it had developed a tiny oil drip, maybe 4-5 spots a night in the garage. Took it to the dealer as it was still under warranty and they knew what the issue was immediately. The seal on the oil cooler can be damaged pretty easily if the oil filter is over-tightened after an oil change. It's a really easy DIY if you're out of warranty.

 

Thanks for the info! I'll look into the oil cooler. This is a great relief for me

 

I replaced the oil cooler ring last night. Something that was strange to me though was that the dealer gave me not an orange o-ring like some of you have described in other posts but a black o-ring.

I also noticed that the new o-ring was slightly larger in circumference, however I was able to fit it in the o-ring groove of the oil cooler. Hopefully this is where the leak is coming from. I suppose I'll find out soon enough. Thanks for the tips!