I have an ST3 Am about to do an oil change, but due to the short journeys I tend to do I suspect there maybe some condensation in there. For this reason I think a flush out would be the order of the day. My question is, would it be ok to use any old 10/40 oil just to run it for 50 miles or so to flush it out? Are there any recommendations for what I should do? I do have Shell Advance ready to go in once it's cleaned, if indeed it does need cleaning. Thanks
I'd just run it until it is really hot with the old oil still in, then drain it after it has cooled down a bit (you don't want it to melt through a plastic drain tray!) but is still warm. I think the historical use for flushing was when old fashioned oils and fuels (and engines) tended to build up far more in the way of sticky deposits inside an engine. Most moisture is going to boil off on a longish run, and what remains should be emulsified with the oil and come out with it (I assume you don't have obvious thick soapy sludge under the filler cap or in the level window? A bit of condensation in the windows is not unusual though).
Have a look in the oil level window to see if there is white moisture or condensation in there. Best to go for a decent ride to get proper hot maybe even in traffic to get the fans operating. Then drain and refill as needed with the proper oil. Unless you have popped a head gasket or there is free water in the oil then it should be fine
I'm with Mr.R, If you're really that concerned just use a cheap oil and get it lovely and hot on a spirited run. That should be enough to sort out condensation in the engine. Then replace with your oil of choice. Flushing oil makes me nervous as it's very good at dislodging other detritus particles, which if your engine is of unknown provenance could cause premature wear by getting stick in pickups et all. Luckily this is more cars than bikes though. MrR, we used to run our race engines in like that to bed in rings and make sure bore glazing was kept to a minimum at one company I used to work at who ran endurance racing gtr's
As above, a good long run will help but another tip is to disconnect the hose from the breather at the back of the rear cylinder, leave the bike and let it run for a while and get really warmed thru (hot). Having the breather disconnected will allow the moisture to vent to atmosphere rather than into the breather system. There's quite a bit of volume in the breather system and the moisture that's vented can/does condense in the catch tank and hoses. Once the motor is turned off, this runs back into the the crankcase... The breather has a drain hole in it to allow this.
