On 8/6/15 9:40 AM, Stormin Mormon wrote:
On 8/5/2015 8:32 PM, J Burns wrote:


My mower manuals recommend 30W over multiweight, but the 30W that's
readily available here is SA. Is it bad to use SA in a mower engine?

I think they grade oils SA through SF, based on
some quality grading or other. I can't remember
what. But, my SWAG is that SA quality grade is
fine for lawn mowers.

I dumped in a quart of SA last time. I can see you're no bigot because
you're so tolerant of my ignorance. I've decided I was wrong.

When I've opened small engines with a lot of use, I've been amazed at
how clean they were and how little wear I found. Modern oil must be a
lot better than what small engines used decades ago.

Unlike SB, SA has no additives at all. The API recommends SB for mowers
but says SA is good only for hinges and air filter baths.

The engine manufacturer's recommendation of straight 30 may be outdated.
At one time, the additives that thickened multiweight oil would wear
out, but that seems to have improved. At one time, maybe thicker oil
would give better lubrication when you first cranked an engine that had
been sitting for weeks, but I'll bet modern additives have helped.

I've been letting engines warm up before draining oil, both to drain
faster and to carry out as much dirt as possible. Multiweight oil would
drain better than straight 30 cold, and I get the impression that
detergent oil will carry out dirt without being stirred up. No more hot
oil on my hands!

One problem with straight 30 is that it can take a long time to get a
good dipstick reading, after I add oil or even after I pull the mower
out of the garage.

It looks like it was pretty dumb to use 30W SA. Thanks for not pointing
it out. I want everybody to think I'm as smart as average!