I've been fighting a mid PTO shaft oil leak for months on my 855 tractor. For numerous reason, I have not yet been able to make the required seal repairs. Without going into all the details, I just want to pass on to other members my recent experience with Lucas Hydraulic Stop Leak & System Booster. This is in no way an endorsement of the product or a suggestion that you use this product in your tractor's hydraulic system. This is simply a statement on my own experience.
I have a badly worn oil seal at the mid mount PTO shaft. I would lose about two gallons of hydraulic oil leaking out at the shaft after running the mid mount 72" mower over about 2-2 1/2 acres of grass & weeds. I saw a bottle of Lucas Oil additive for gas engines. I got interested in the product & went to their website (just google Lucas oil) to look at the product. On the site I found they offered a Hydraulic System Stop Leak for worn seals & leaky systems. I decided to try the product to see if it would reduce the size of the leak & Low Vis oil loss.
I bought a gallon of the Lucas & it was expensive. Paid $33. & change with the tax. Got it home & opened up the bottle & really got cold feet over using it. The stuff is dyed red & it is really really thick like Molasses. Compared to the Low Vis hydraulic oil that's in the system, it makes you think about what will this heavy stuff do in the system. Then I also questioned why am I shelling out $33. for a gallon of this stuff when Deere Low Vis oil here is $18 a gallon. Anyway I decided to put it in. On the first try, I put in a full gallon of the stuff & then toped off the oil level with about a half gallon of Low Vis to bring the level up to full on the dipstick.
Went out & cut 2.5 acres of weeds about a foot tall & thick. Got done with no issues from the use of the Lucas. Parked the tractor & kept an eye on the leak. Noticed that I still had the leak but it was now leaking slower & less oil loss. So I waited & watched over several days. Then I decided to try again with Lucas. I installed another gallon of the stuff & again toped off the system with Low Vis oil. Went out and mowed the same 2.5 acres, parked the tractor & the leak has fully stopped for now. I don't know if the leak will return, but right now it's gone. I AM not suggesting that using Lucas Oil will be a good thing long term. There is no magic substitute that can replace a full mechanical repair.
The Lucas product, for now is helping me until I can get to the repair. Based on my experience, the product takes some time to work its way into the seal & swell it up to stop the leak. Also the 855 holds 5 gallons of Low Vis oil. It took me two gallons of the Lucas installed to stop the leak. Also I have no way of determining if the Lucas changed the viscosity of the Low Vis oil, however examination by feel of the oil & visual examination it appears not to have changed the Low Vis BASED ON THE TWO GALLONS OF LUCAS I INSTALLED.
If MY oil seal had a tear in it, I doubt that Lucas or any additive would have worked. So what I believe I have is a badly worn oil seal at the PTO shaft. Keep in mind that using Lucas is just a temporary treatment AND NOT a repair. But sometimes a Band Aid can save the day.
A word of caution- I had a difficult time locating the product in my area. You will not find this stuff at your local Wal-Mart or Auto Parts store for the most part. This product is specifically labeled for use in HYDRAULIC SYSTEMS. Do not use the Lucas stop leak that is designed for gas engines. The Lucas I used is For hydraulic systems. I finally found it at a large NAPA Store & machine shop about 12 miles from my house. If you can't find the stuff, contact Lucas for dealer help. Maybe you can order it direct from them?
For now-its working & I'm not having any issues in my transaxle beyond the leak. So I guess the Lucas is safe to use & while really thick it appears to mix well with Deere Low Vis. However I don't know how much Lucas you can put into the system safely. I suppose you could call Lucas and ask if you have questions on how much you can safely use. Lastly, I'm just stating my experience with the product, which so far has been positive.