B&S Oil Recommendations
It appears that Briggs makes the same recommendation for oil regardless of engine type from the ancient side valve models to the more modern OHV engines. Two points of curiosity to me are:
1) The use of straight 30 Weight oil
2) The acknowledgement of only 10W30 muti-viscosity oil
Multi-vis oils have been in use for more than half a century and were developed to overcome the tendency of straight weight oils to become too thin at high temperatures to provide adequate lubrication. B&S indicates that air cooled engines run hotter. So why is HD30 still recommended?
Briggs also states that oil consumption may be increased when using 10W30 at higher temperatures. Is not that why we have 15W40 or 20W50 weight oils? And, since a 10W30 oil is supposed to have the same viscosity at high temperature as a 30 weight oil the claim of increased consumption sound a little suspect.
My JD 314 has a Kohler side valve engine. It likes HD30 and does not tolerate anything else. I tried some Valvoline 20W50 racing oil which I had left over from my RX7. The engine drank a quart of oil over a 25 hour change interval. It never used oil with HD30. Then again the design of the engine dated back to the days of the dinosaurs from which the oil was made :-)
So now I am puzzling over the best oil to use in my new Scag Freedom Z with a Briggs Intek OHV engine. The dealer claimed that Briggs sent them a service bulletin recommending only HD30 in temperatures over 90F (although they could not find a copy of it when I asked).
In my prior mower, a JD SST18 with a Briggs made OHV V twin engine, I used 10W30 per JD recommendations. It never used oil between changes over 9 years of use.
My instinct tells me that something like Rotalla T 15W40 would be ideal for this application. The mower will be run mostly in the summer but on occasion during cooler weather.
Comments or snipes?