After changing the oil in my SV today after winter storage, I noticed during topping off that the oil (Motul 5100) looked a bit foamy and not so clear. Before storage, I had put some cheapo Motomaster 20W50 motorcycle oil in the bike. I did not use a fresh oil filter during the oil change; used the same as I had before (used it only for about 1500km before storing the bike).
1. Could it be that the left-over Motomaster oil (perhaps in the oil filter, although I tried my best to get rid of it) might have reacted with the Motul 5100 to cause the foam? The foam is just a line of very tiny bubbles at the top of the oil level.
2. Is there any reason to worry here?
I doubt if it's a reaction between the oils, probably a result of condensation with the bike being laid up for a long period.
After a lay up, I'd stick cheap oil in the bike and take it for a 20 - 30 run. This should heat the oil up enough to boil off or absorb any moisture and give the internals a good wash. Then change the oil and filter to your usual brand for the season.
this is my...boomstick!
It's likely water contamination. That's why we change it out after storage.
If you don't change the filter, you leave about a couple hundred ccs or so of old oil in there and whatever is in that oil, is in the new.
I heat the bike fully on the storage oil, i.e. take it out for a few gentle round the city turns, then drain it, bump the starter a few times to pump anything in the passages back to the pan, take the filter off and start fresh.
I just use good old Castrol 4T and a factory filter.
Thanks FF and Crotch.
Yeah, I knew it was not the best idea to reuse the oil filter, but did it anyway. Oh well.