bargee1759

Yes you are right BEngo, I mislead! You quote straight from SEA J300 & I was thinking of the single grade ashless dispersant aviation piston oils where the "W" is a dfferent thing & I should have said additives not detergents too. (just to add more confusion W100 aviation oil is SAE50!) I'd already been up 19 hours when I posted that so next time I'll get my facts straight first. I'm going to sit in the corner now with a hat on sporting a large "D" on it.

HI Folks, I'm new here, so I hope this isn't "old news!" The "W" in oil labeling means it's got detergents in it & "straight" oils don't. In a previous life involved with piston engined aircraft, a newly built or rebuilt engine was always run in using "straight" oil for its 1st 50 hrs or so, then swapped back onto "W" oil. If this wasn't done, the cylinder bores would glaze over & the piston rings never bedded in. They were also single grade oils, not multi-grade. I also have an HA2 & am going through the same debate - Tim's figures are correct from the Lister manual, but the Morris product guide pushes me towards their Gold Film 30, so Madcat's post is heartening!