Hey all,

I'm doing a full oil change on my 91 FXR and as I'm running it to pump the old oil from the engine out the filter hole I notice the new oil coming out is a bit foamy.

Is this normal considering the scavenging nature of the oil pump? After it runs through the filter and back into the tank I would expect it to be less, or not foamy at all.

Is this normal for this scenario or could there be something else going on?

BTW, it's Motomaster Formula 1 20w50 oil, not HD. It was way cheaper.

Cheers.

 

Mine does the same thing.
Don't worry about it.

 

Mine foamed when I had Castrol in it, went back to HD and it doesn't foam. Something about regular motor oil doesn't have an additive in it that motorcycle oil has. Just what I heard, but I prefer my universe less foamy.

 

What you are seeing is the affect of the cocktail of additives in that brand and grade of oil - which differs widely through the industry. Auto oils are not particularly suitable for our bikes, but unfortunately H-D is notorious for not helping us find alternatives. Just occasionally we can learn that a diesel oil is a more suitable alternative, of designations CH-4, CI-4, CJ-4, as per the owners manuals of my later year bikes.