sorry I make stupidly over-detailed threads and can't edit them shorter once 10 mins passes.. In this thread: https://www.lawnsite.com/threads/fi...ox-oil-change-worldlawn-world-lawn-28.480418/ Don't bother reading ^, just look at pics to get an idea for size of the 3-speed gear box, it's on a small 28" walk behind mower. Gearbox is about the size of two 12oz soda cans laid side by side. The fill cap shown is about the diameter of a US nickel, use that for scale. Basically all that thread is asking is how much oil should I put in it? (2nd post is notes for future reference). Worldlawn made that transmission themselves but their manuals have conflicting info for this 2006 model. Manual says use 8oz 75w90 or 80w90 gear oil, but later in the same manual it says use 16oz SAE 30. It is an oil gear box as you can see black plastic-like oil seals at the axle exits. It doesn't use thick peanut butter type bentonite grease which eventually hardens and doesn't lubricate and usually those gearboxes aren't sealed as well as an oil one since bentonite is so thick. And it doesn't use grease - the newer models use a different but similar trans which uses grease. I put a dipstick in the fill port and it looks like oil to me is in there but has some thicker stuff mixed in but might just be thickened oil globs. I bought 75w90 full synthetic gear oil. Should I also add an additive, if so what? Basically how high up should I fill the gear box?? As it is now, there's about 2 inches of air until a dipstick hits oil if dipped down the fill port. A homeowner had this mower previously only for himself, and I doubt he changed the gear oil therefore possibly making the level it's at now incorrect, so should I just measure what drains out and add about .5oz (account for oil still in box after draining) and go with that number? It works perfectly how it is but I doubt the initial 80 hour break-in oil was even changed. The manual says use 8oz gear oil but also says later use 16oz SAE30. Worldlawn since removed all previous manuals and there's just 1 manual to cover all the older models that says 8oz gear oil, but one older manual did say use 16oz SAE30, and even 16 oz seems like it's not enough based on size. Maybe because SAE30 is thinner than 75w90, it's OK to use 16oz of thinner SAE30 vs 8oz thicker gear oil? I won't put SAE30 but I emailed WL and they told me use 8oz 75w90 or 80w90 but it seems that would be too little and maybe it's just a typo being passed on from an older manual. THANKS!!!