Miata Mailing List: January 1999, Message #37

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On Thu, 31 Dec 1998, ivan white wrote:

> Have noticed a peculiar smell from the rear-end recently which I had been
> attributing to hot brakes (Put in metalmasters this fall).  A couple ramps
> under the rear and I discovered a leak from the left (driver's) pinion axle
> seal.  I changed differential oil to the infamous MTL  oil about 6 months
> ago.  Car only has 36k and not driven all that hard. 

Why are you running Redline MTL in the diff?  MTL is Manaul Transmission
Lubricant, which would be much too thin for use in a diff.  Should have
put in Redline 75W90 gear oil.  Needless to say, the thin oil would have
run hot, which probably brought on the leak.

> Could this be the source of my leak?  If so, has anyone had any luck going
> back to dino oil in the rear?  I've read about the head-gasket leaks with
> synthetic oil in the engine but nothing like this for the rear-end.

Run the 75W90 gear oil after you replace the seal.

> The silly oil seal is  a $6 part but a $150 install from the dealer.  Don't
> think I have the tools or mechanical know-how to pull the axle and indstall
> a new seal.  

It's actaully not that bad a job to do, but if one can leak, the other is
sure to follow...I'd do both stub seals.  Removing the axle shafts is just
a matter of four bolts per side and a lot of wiggling to make them drop
down.  The stub shafts will pop out (they're held in with a ring) with
some prying.  Once they're out, pry the seals out, and use the old seals
to protect the new ones as you gently hammer them into place.

Regards,

Richard Dekker, Edmonton, Alberta, Canada, MCofA #41997
Founder & President, Wild Rose Chapter - MCofA

1990 MX-5 Miata - Bell Stage III+ - "Turbos Blow"
1973 RX-3 - Rally Port 13B - "Pistons Suck"