Small Engines (Lawn Mowers, etc.): Troy Tiller Trans Fluid, gear oil, trans fluid

Question
Hi John,

I have a 1974 Troy Bilt Horse that I purchased earlier this year. Currently, I am having engine problems (which you have already answered), and am waiting for parts to come in.

The tiller has been sitting in the garage, and I noticed that transmission fluid is leaking from the tiller housing. I purchased seals and gaskets to stop the leak.

My question is, what fluid can I use? The manual from 1974 says to use SAE 90 or SAE 140 gear oil. I can't find this locally (I've tried three different auto places). I've heard that you can't use multi-viscosity gear oils in these old tillers, is that really true?

I've checked the Troy-Bilt website, it seems they've been using 85W-140 for years now. Have they changed some key parts, or is this fluid essentially interchangable with SAE 140?

I've been able to find 85W-140 locally, but it's not synthetic. Does that matter?

Also, since I really have no idea what kind of fluid is in there (since I bought it used), can I just add 85W-140 to top off the level, or do I need to drain and replace it all?

Thanks again, lots of questions here!

Mike

Answer
 Hello Mike:

 I Suggest you Drain and Clean the Transmission and then Add the New Oil. I Use and Suggest the Use of Lucas Gear Oil SAE 80w90 or the Synthetic SAE 80w90 Gear Oil. The Synthetic is the Best. Hope this Helps. I am here if you Require more Assistance. Let me know what Happens, Please. Thanks.

 Good Luck

 Respectfully

 John