Hi, I changed the oil in my TRS drives on my Magnum 27 for the first time yesterday. They are supposed to need 2.6 quarts including the reservoir but after filling 3 quarts there is still nothing on the dipstick. Where is the oil going? I can't find any leaks anywhere.

Has anyone had the same problem?

cant fill thru dip stic. remove top 4 bolts from top cap fill there. the dipstick is just a resevoir

I put about 3 in the drive and about 1 to fill reserve. Ask my upper gear set how much it liked the 2.6 quarts!

Interesting, so you put 4 quarts, the same as for the TR-drive. How come Mercruiser specify 2.6 quarts? Seems like a bit to big a difference.

By the way I have been filling through the oil plug not the reservoir.

What he said

You are doing it correctly. Fill from the bottom to the top until fluid comes up to the resevoir.

That way it makes sure you have no air in the casing.

Pull the top cap way easier. Inspect the top gears look around and check the bearings. That drive holds alot of oil and those pumps suck. I do mine every 2 races pulling the caps.

I can't remove the top cap without removing the rear cap because of the hydraulic steering, Is it still ok to remove the rear cap without draining the oil?

No. I wouldn't waste my time removing all that steering hardware. Just put it in through the top vent hole in the drive. Just give the prop a spin every once in a while as your putting it in. I fill mine through the top and have never had a problem. If you get 3 quarts in you know your good. Pumping in from the bottom just makes a big mess. Don't know where you came up with 2.6 quarts but my manual says 3 for the TRS and 4 for the TR. Then your reservoir will hold 1 more so you need 4 qts. total for each drive including the reservoir. After it sits a few hours and everything levels out check your dipstick and correct if needed.

Oil changes are subject to the laws of physics. If you want to be absolutely certain that all air is expelled from the gearcase(s); filling from the bottom up is the proper way to obtain certainty. The drain and vent are both 3/8 16 thread, and any pressurized garden sprayer from the local hardware store makes the perfect gearcase filling pump. A 1/8 npt nipple will easily thread to 3/8 16 and clamp in hose. The "only" oil that will provide longevity is Mercruisers "high performance" gearlube. The original oil specification is totally outdated as are the factory preload specifications.