Briggs and Stratton 4 hp motor

**smoky** · 31st December 2007, 09:22

“The 3000-mile interval made sense when engines used single-grade nondetergent oils. But with the latest oils and car designs, it's no longer necessary to change oil that often under normal driving conditions.
Synthetic oils, because of their better properties, need to be changed less often, at intervals up to 25,000 miles or more.”
Chemical & Engineering News
ISSN 0009-2347
Copyright © 2006 American Chemical Society

Interesting thought - If you're not concerned about vioding a warrenty I might consider that advice from American Chemical Society, I wonder who they are?

Mind you doing an oil change makes you feel very caring and responsible - have we been brainwashed?

**What?** · 1st January 2008, 19:46

Originally Posted by smoky

My old lawn mower had a Tecumseh engine – never changed the oil in 12 years, motors now running a friends go cart because it out lasted the mower body.

It must have been a dud - Tecumseh engines are designed to blow up five minutes after the warranty expires (said the man with a broken B&S...)

**huck farley** · 4th January 2008, 07:26

Originally Posted by smoky

Of course you can use a multi grade synthetic in your old B&S. Oil grades are based on a viscosity range at a standard temperature; the higher the viscosity, the higher the SAE grade number. These numbers, which range from 0 to 50 or higher, are referred to as the "weight" of the oil.
The letter "W" is the oil's cold-weather weight, as in 10W, which is gauged by the oil's viscosity at 0 °F. The warm-weather weight is based on the viscosity measured at 210 °F.
High-molecular-weight polymers improve the viscosity and are added to oil base stock to create multigrade oils that maintain the ability of the oil at different tempretures. At cold temperatures the oil is thick and the polymers are ‘balled-up’, and at warmer temperatures they expand to prevent oil from thinning out too much, maintaining a constant viscosity and protecting your engine in all conditions.

Thank you for the post. It is really assuring to know I have done the right thing.

I have cut the lawn twice now since running on Q8 10-40 fully synthetic oil. In that time I have kept a very close eye on the oil level, and looked for any smoke coming from the exhaust.

I can report that it is doing neither. Also I posted in a previous post that the knocking seems to have disappeared when running over some real thick and long grass. I have to put that down to the Q8 oil. As I can think of no other reason.

Also Thanks for explaining the properties of the various numbers we see on the oil we purchase. I found it to be very informative.

So to all posters that called me a dickhead, firkin Idiot, Muppet, silly carn't and other abusive and uninformed posts. It is you people that need also to take Smokys post on board. I had a gut feeling something positive would pop up sooner of later.

This forum is a great leveler, and also very informative. It just goes to show that a day you don't learn something new. Is "indeed" a day wasted.

Thanks Smoky for pointing the facts out. That it is indeed very safe to use a synthetic oil in Briggs & Stratton, lawn mower engine.