Export thread

I've have an old Coast to Coast front tine rototiller. Old but runs like a champ. I'm in the process of replacing the front tine gear oil with 80W-90. This tiller has a small bolt up high which I know is the overfill hole. My question is that down low on the housing there's two bolts. I expected one drain bolt but there's actually two. I unscrewed both and drained the oil out both holes. When I refill the oil through the overfill hole, does that oil fill up both sides? Why are there two drain holes but only 1 filler hole? Does oil going in the one overfill filler hole split and go to both parts of the housing with drain holes? I just want to make sure I'm filling it back up properly. It took just shy of 1qt of 80W-90 before oil came out the overfill hole. I hope the pics show what I'm talking about as it's hard to describe. Thank you.

Remove both, fill oil in the big hole and see if oil seeps out the overfill hole. I think it will. Your gearbox looks similar to the Gilson tiller box where there is no overfill hole yet oil seeps down the shaft.

I don't think that top hole is a fill hole.

The lowest hole will be the drain hole. The next hole up will be the fill hole. Fill to the bottom of this hole.