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Poor MPG/gear oil smell after trans oil change

Old 08-17-2006, 05:32 PM
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Exclamation Poor MPG/gear oil smell after trans oil change

I recently performed the 30K services on my '04 RX8. After the tranny oil change, I noticed the smell of gear oil in the cabin of the car. I figured that I must have had some oil on my hands when I touched the steering wheel. After several cleanings and ALOT of air fresheners, the smell remains. Is it possible that I overfilled the trans oil and that is causing the odor? I have also noticed that my MPG has drastically decreased since the services. I was getting 19-21 mpg. I am now getting 10-12 mpg.

Anyone have any ideas?

Todd
Old 08-19-2006, 06:52 AM
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I live in the moutains of VA. I changed my fluids to redline about 3 weeks ago. I only smell mine once in a while as I cross the moutain where I live. No too strong but enough for you to notice. If you keep the revs high alot you will smell it regardless. I used to smell it alot when I had a 91 GTU but it was cause the rubber boot thingy (seal) under the leather shift boot had a small hole in it. May want to check yours. Over time the heat from our engines/trans and shifting does a number on that rubber seal. My buddy who has owned at least 6 RX7's has had the same problem.
Old 08-19-2006, 08:22 PM
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Interesting.

I have an '05 with 5000 miles and changed to Royal Purple 75W90 in the MT about 1000 miles ago. Since then I have noticed a hot oil smell once the car is fully warmed up that is noticeable if I sit at a stop light for a long time, or when I get home and get out of the car. I have checked repeatedly for leaks or signs of oil anywhere on the underside of the car (including housing seals, oil pan and rear diff also) and can not find the source of the smell. Maybe it's coming through my shifter also. I'll have to put my nose down there when I get home tomorrow.
Old 08-19-2006, 10:28 PM
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It only takes a little bit of a residue of gear oil on something hot to make it smell, and smell for a long while. I changed the gear oil in my tranny and rear diff 14k ago, and right after sprayed degreaser and water on everything under there and never smell a thing or had any problems.
Old 08-21-2006, 09:10 PM
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Originally Posted by Brice-RX8
It only takes a little bit of a residue of gear oil on something hot to make it smell, and smell for a long while. I changed the gear oil in my tranny and rear diff 14k ago, and right after sprayed degreaser and water on everything under there and never smell a thing or had any problems.
Thanks for the info. I wiped up all spillage with a cloth, but never really CLEANED it. That will be my next job.
Old 08-21-2006, 09:49 PM
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Originally Posted by toddman
I was getting 19-21 mpg. I am now getting 10-12 mpg.

Anyone have any ideas?

Todd
how much oil did you put in - mine took a little less than 2 litres (approx. =2 qts) ?
how much oil did you get out ?
what else did you service ? for your consumption to drop that much under the same driving conditions you would have to have done something seriously wrong.
Old 08-25-2006, 11:51 AM
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I added about 2 1/2 qts of 75W90 Castrol synthetic, roughly the same amount that was drained. The other services performed:

flush/refill radiator
drain/refill rear diff
flush/refill brake fluid
replaced spark plugs
replaced stock air filter w/ K&N
rotated & balanced tires
brake inspection

I think the issue with the smell may be too much gear oil in the tranny. When we drained/refilled the trans, the car was not on a level surface. From what I have read, this is a MUST when performing this service. I am going to get it on jack stands today and check the fluid level. I'll keep ya'll posted.

Todd
Old 08-27-2006, 05:14 PM
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i replaced my tranny and differential oil around 3000km ago and still smell it a bit when i get in the car. I put around 1.8l of castrol synthetic 75W-90.
Old 08-27-2006, 05:44 PM
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2 1/2 qts is definately too much !


of the other things -
nothing stands out but filter/plugs/tyres/brakes can all affect MPG .

However to make that much difference you should notice other effects also.
Perhaps when the filter was replaced something got in there that is interfering with the MAF ?
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