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For whatever it is worth

Bought a new lawnmower last year. Having a Briggs and Stratton engine, I thought it would be sure to be trouble free.

After careful break-in with 30 viscosity oil, I decided to move over to Mobil 1, to see if I could really pamper this piece of equipment.

Soon afterward, it started burning oil with a vengeance.

I tore it down, put in new rings, etc, honed the cylinders, and tried again. (Sister had lost the receipt so I had no chance at warranty replacement.)

Sucker lasted a few hours and then was as bad at oil burning as ever.. Couldn't finish a lawn without it fouling plugs.

My local outdoors shop representative told me that B&S had recommended 10-30 at one time but had backed off because of engine failures. Use only 30 wt.

I told him what I had done, and he couldn't give me a certain answer, but suggested that the multiweight Mobil 1 might have done me in. Otherwise, it was just a fluke.

He also told me that the once very reliable B&S engines were no longer of the same character as they used to be. When you re-ring them, use chrome rings or forget it.

Anybody have any real knowledge on this??

Reply to
Larry Smith
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Larry Smith wrote in article ...

It is a fairly well-known fact that synthetics are NOT good at seating rings. Since they are so slippery, they keep the rings and cylinder walls from rubbing each other smooth through normal friction.

How long did you use the "break-in" oil?

One hour's stationary use is equivalent to approximately 40 miles of road use - hardly an extended "break-in" period.

Most likely your rings had not seated yet, and your synthetic - as might be expected - simply blew by the unseated rings.

Harder chrome rings only exacerbate the seating problems - requiring even longer "break-in" times.

Try running regular oil for a full season or so, then switch to synthetic - if that is your end goal.

Bob Paulin - R.A.C.E. Race Chassis Setup and Dial-in Services

Reply to
Bob Paulin

I have heard that Briggs quality may have taken a nose-dive recently, especially the smaller (3-horse and less) models. OTOH, my latest lawnmower (bought summer of 1994) with a 6-horse Briggs & Stratton "Diamond Commercial" series engine (aluminum block, iron liner, old-style side-valve flathead) has been happily running on Mobil 1 10w30 for the past 7-8 years, one oil change per season, with ZERO added oil between changes. I don't pamper it.

Sounds to me like a) you may not have broken it in completely before switching to synth, or b) you used too wide a viscosity spread (eg 0w30,

5w40, etc.). Wide-range oils, even Mobil 1, tend to have more viscosity modifiers than narrower ranges or heavier ranges. Viscosity modifiers are a bad thing in high-temperature (air cooled) applications because they "cook" before the base oil does.
Reply to
Steve

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