GM400 age related oil leak
Over the winter, when the cars sitting there for 6 weeks or so. It will start to loose oil from the Bell housing. Do these additives actually help

If your car is loosing ATF I would suggest its the torque convert fluid draining back into the sump of the trans and seeping past the seal. If thats the case try running the engine once a month and see if that stops the leaks.


I wouldn’t trust an ad that has bad English. (Too instead of To)

Also, sitting for a while, if it indeed leaks because of that, just running again should help swell up the seals and stop the leak.

If you do want to add anything, I always trust Lucas Transmission Leak additives.


Thanks gregma
I wouldn’t want that particular product It was just an example. I would probably go lucas as well

I sometimes added Lucas to old transmissions as a preventative measure, but recently discovered this, and now use this instead.

I have no leaks, but I’ve noticed improved shifting in my XJS after just a few weeks. It has very good reviews, and seems to not be snake oil. I’ve added it to my other cars with high mileage transmissions, and so far so good.


Now that makes sense! I always took for granted that the front seal just went out, never thought about the fluid from the torque converter draining back and pushing past! Duh on me!

1 Like

Just personal experience from when I was repairing the rear valance of my S11, was nose down for a few weeks (slow worker) went into the garage one day to a huge puddle of ATF. :frowning:


Yeah my Malibu has been sitting in my barn for about 5yrs :pensive::pensive::pensive::pensive::pensive: talk about a slow worker smh. Needless to say I too had a big puddle after a few weeks, but never even thought about it not necessarily being a blown seal. On the plus side I just got “approval” from the wife for new carpet for it! It was my first car, and I’m 43 now, so I really want to get her back on the road where she belongs!

A wee bit of advice, from 20 years into your future: do anything you can to get it back OTR: even if imperfect, the time lost while it sits…

…is never recoverable.


I absolutely plan to. If it weren’t for my motorcycle wreck 2 years ago, and then buying the 2 Jags of course, it would have been. I have no problem driving an imperfect looking car, and my XJS with it’s tatty paint attests to that. I learned that lesson from my dad. He had a 1950 Ford Victoria 2 door when I was little. He did body work on it, had the flat head rebuilt by a guy that used to race them, and the trans refreshed. He was constantly working on it, then one day he decided he needed money and sold it to his one uncle here in Pa for about $500 (we lived in South Carolina at the time). Needless to say he still to this day frets and fusses at himself because he never actually tried driving it! We came up to visit the year after my dad sold it and my dad asked the uncle if he would be tempted to sell it back to him. The uncle replied “Oh I sold that for $4500 pretty much as soon as I got back up here!” I guess that’s how it goes sometimes, but I learned the lesson

1 Like

Just got some of this myself. How much did you put in your Jag? The bottle says 1 ounce per quart of ATF and the XJ-S holds maybe 9-10 quarts of ATF. Did you go with their ratio or more or less?

The full 10 oz. TH400 surely holds 10 qts.

My other cars, I used 8 ozs.