Counter rotation lower end going out?

Greetings,
Spent Saturday changing oil in lower units on 1997 Yamaha 200's. Last done 4/08 seemed fine. Only put 25 hours on since then. Saturday, right side oil looked new, but left oil (counter rotation) engine lower unit oil smelled bad and was black. Had metal filings on end of lower bolt. If I just use it til it goes bad will it cost more? Does it mess up more things if it goes bad (my tendency) or have the lower unit replaced on the left side before it gives me any trouble? Advice/thoughts appreciated.. Going to keep to the bay and not go way out for a while.
szoobie

[robert graham]

you better replace the seal on that lower unit before that water in the oil really screws up a lot of expensive gears and bearings, if it hasn't already. if your metal particles look like a fine powder then you're probably O.K., but larger pieces of metal like chunks of gears and things don't sound too promising. good luck!

[jf123]

Did both units have the same type of oil and equal amounts ? Was one lower replaced before ? Black dosen't necessarily mean it's bad. Small metal filing on the end of the magnet are normal. If you have water intrusion the oil would look like cofee with cream. Replace the oil and monitor.

The oil looked more like coffee without cream. It had a strong smell to it. I let a Yamaha dealer do the lower gear oil in 4/08 and this is the first time into it after that. I did not check the work, did get charged for it, so only assume both motors were done. Dealer did comment to me that the counter rotating engine works a lot harder and I should change the oil 1/2 way through the season. Since I had only done 25 hours I did not bother. Makes me think he did do the oil. Has been great in the past. The metal filings were small but seemed to be about the size of a BB. Such a contrast to the other side that was perfect.

[jf123]

If it was mine. drain/refill/monitor. Does the owners manual show different maintenance intervals for counter rotation?

Appreciate the input. I think I'll try monitoring it closely for a time. Thanks

[robert graham]

if you really think about it, one of the main reasons to change the lower unit oil is to see if a seal is leaking, so if you already know you have a bad seal then now is the time to replace it. water, especially salt water is pure hell on gears and bearings...I've seen it. Good luck