First a couple of questions, what year is the car, which motor does it have, how many miles on the motor? Second, you'll need to diagnose which gaskets are leaking on the motor and replace them.

On a side note, i've never heard of motor oil eating motor mounts. a motor mount is generally a rubber product which is made of petroleum (oil is made of petroleum as well assuming a conventional oil). did a shop tell you the motor oil was eating the motor mount? I ask as this is the first time i've heard of such and thing. can you provide more details as to why you would think it was eating the mount? i could be totally wrong and not know it.

 

I have a 2006 Chevy Impala(Old Police Car), I changed the right lower mount. Motor has 116K miles on it. Ill look into the gaskets.

I should have taken a picture of the mount and the boot on the rack & pinion when the oil seemed to have corroded the rubber. I also looked at a Video on youtube and the guy had the same issue with his impala. I went and got it inspected by a Maryland State Inspector and when i looked at it i seen it was sludge looking.

Here is the youtube link as to what i saw with this guy changing his motor mount

 

Agree with the above. Have to figure out where it is leaking from to know which gaskets you need to replace.

Far as the oil eating the rubber in the motor mount, my daughter told me she was told the same thing by a shop on her 2001 buick. I had never heard that before then either.

 

Oil will eventually degrade the rubber (mount).

 

+1 to sheila. synthetic rubber is petroleum based and oil-based products tend to break it down.

 

Yeah, oil is bound to degrade the the rubber, agree.

 

I need to replace my rack and pinion as well as the lower motor mount because I had leaked oil from my lower and upper gaskets and the covers too. It cost me a $1350 but included a few other things also. I still need the rack and pinion as well as the lower motor mount and some brake work.

 

Good luck let me know how that goes!!!

 

Can I lower subframe instead of lifting engine for this motor mount replacement job?

 

It will be very difficult with just lowering the sub frame. Trust me I did it last weekend. I had to jack the engine up to even get the mount to come out. But if you do it with just the sub frame being lowered ... Kudos!!!!

 

I asked the question just because I would like to replace crackshaft seal while working in the same area, and will have to drop the subframe anyhow. Apparently, GM changed harmonic balancer/crankshaft pulley design in 2007-2008 and removed holes. I have to use a regular gear puller

 

I didn't know all Impalas of 7th and 8th gen have the same motor mount. Rockauto lists the same mount for 2001-2011. Here is a good writeup. 3100 Lower Motor Mount Replacement Write-Up - Frequently Asked Questions (FAQ) - W-body.com Community It is 2001 3.1 but exactly same setup as my 2008 3.5L.

A few things not mentioned in how-to video/writeup.
Wiring harness needs to be loosened where ziptied to radiator fan, chassis, etc, that goes not go up and down with engine. Front right ABS cable is getting in the way. Disconnect at ABS and push the cable aside.

I thought engine would go straight up and down as jack goes up and down. Engine moves sideways, too. If this happens to you, push/rotate jack and engine will come back to the right position.

 

Just got finished changing mine.... the old mount was collapsed and disgusting (fluid leakage)

It really wasnt that bad at all considering its almost 2:30 PM here and I pulled the car into the garage around 11:30 AM


there is no need to lower the subframe or loosen the wire harness as previously mentioned.

If you do have a front strut bar you need to remove it in order to get the engine jacked up high enough.

I guess when I take it for a test drive hopefully all the banging and creaking over bumps will be gone

 

Update, forgot to mention all 4 brakes done, front rotors replaced, bled lines, rack n pinion replaced, suspension in front replaced. Now it shut off on me. Ran a diagnostic check. Map Sensor will be replaced. Found a code for throttle body and saw it was not tightened properly!!! I admit I was pretty pissed after I paid someone to work on the gaskets because I don't have the tools (mic) to make sure the heads are level and the fact I never have done it. I am replacing the MAP sensor soon myself. Should take like 5 mins. Hopefully she starts right up.