I just got hit for $300 to change the gear oil (a ten minute job that uses less than a quart of oil) and clean a screen by a Yanmar authorized place, but the kid that changed the oil was no mechanic. This should be done at the 50 hour mark along with your first oil change. It's not in your Yanmar engine operation manual, because the engine gear is purchased separately–but don't forget to do it. In the black canvas case of "manuals" is a manual covering your gear box telling you it's service intervals. You can download it here by searching for KMH40A; which is the gear model, but you have to pay for it:
http://boatdiesel.com/PDFLibrary/Search/index.cfm I can't seem to find a free download on the Yanmar site. Bummer.
If the shop had checked your shaft alignment (takes a few minutes with a feeler gauge) and then had to loosen engine mounts and whatever to realign it, then your cost would not be so bad. Wait, you did have the shop check the alignment–right?
Next time I will change the gear oil myself, as should you, as everything is all exposed in front of you with easy access. Sounds like you still need to do it and check the shaft alignment. I found a loose engine mount and there are other posts about loose screws at the coupling to the gear which need replacing when found loose. Get used to checking this stuff yourself and saving a ton of money.
Every year you need to change the engine zincs (I've posted elsewhere on this on TugNuts). I had the kid do this as it's a two minute job and that was bundled into my $300 fee. However, I was charged $50 per zinc (Oh, joy!) for just the part:
Even with Canadian duty, how much can this $17 part cost you? I bought it on Boatzincs.com and there are likely comparable Canadian places. Its a bit more, but still way less than $50 to buy it from Ranger. BTW, you need two of them. You can actually just buy the zinc part for about $7 and screw it into the cap when the old zinc disappears.
But, wait there's more! The oil change can be done by any mechanic. But you want to have a receipt proving that you used Yanmar (or equivalent) synthetic oil which costs about $10 per quart. It's not the mechanic, but the oil that's important, make sure it's stated as Yanmar synthetic on the invoice for your records.. My $80/hour yard mechanic did the job in an hour, and most of that is waiting 20 minutes for the engine to run and warm the oil to make if possible to suck out of the engine dipstick. It was a toss-up as to whether I should buy the motorized sucking device to pull out the oil for $150 and then have to store the big thing, or hire a mechanic. Being lazy, I hired the mechanic. The filters get changed at 250 hours as noted by the previous poster. They ain't cheap by any means. And, they are hard to find even from your local distributor as our engines (Yanmars that is) are so darn new–buy them and keep spares as I did from Andrew at Ranger, recently.
I am getting this response from different Yanmar factory authorized mechanics (which we all try to use, at least before the warrantee runs out): "Wow, is that the new common rail thing-a-ma-bob engine? I've never seen one before..." I'm done with them and their high expense as they figure the engine out on my nickle, and now trailering the boat to the distributor who has mechanics who, at least, have seen the engines before!