OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines Engine oil for 4 stroke mowers.

Can I use a good quality car engine oil on a Briggs and Stratton 4 stroke mower, or do I need a special weight oil for mowers? Any ideas?

The B & S manual says use SAE 30 above 10 degrees C, and 5W-20 or 5W-30 at lower temperatures. If not available at 10 C or more, use SAE 10W-30. In other words, ordinary engine oil is fine for Australian conditions.

grumpy,

Never use normal engine oil in small 4 stroke engines because they do not have an oil filter to clean the oil. No oil filter using engine oil tends to create more ware in which case you then cancel your warranty.

Bruce, I don't yet understand your point. It is possible that B&S has published a newer specification than the one given in the "General Information" section of their overhaul manual that I downloaded from the internet, but ordinary engine oil meets the specification in the manual I have. They say, "Any high quality detergent oil having the American Petroleum Institute classification "For service SC, SD, SE or MS" can be used in Briggs & Stratton Engines". That is the normal specification of automotive engine oil. It is worth noting that B&S prefer straight SAE 30 oil to multigrade oil, and all ordinary engine oils these days are multigrade. However B&S say multigrade is satisfactory if straight SAE 30 is not available.

The engine has no oil filter whether or not you use some 'special' oil. That is why B&S require that you change the oil every 25 hours, and more often under dirty operating conditions. Cars used to have to have their oil changed every 1,000 miles before they had oil filters, for the same reason. Also, I do not know what is different about this allegedly-special oil you recommend. Ordinary API-specification automotive oil is the most advanced oil formulation I know of, with two provisos. First, synthetic oil has slight advantages over mineral oil under extreme conditions, which are certainly not encountered in a B&S engine. Second, there are additives that can improve the performance of oil, again under extreme service conditions. For example it is a very good idea to use an oil rated for diesel engines in that kind of engine, because they are rather hard on oils. Racing engines have some really exotic oil additives, formulated for that particular engine.

.

Well gentlemen ..can we use engine oil ..or do we just agree to differ on expert advice?

I would have thought car engine oil these days is to a very high standard particularly considering the value of say a luxo BMW or Merc car engine compared to a relatively cheap 4 stroke lawn mower engine. {anecdotal..not scientific comment}

Specifically has anyone actually encountered damage caused by engine oil. At this point I use B&S oil in the Murray ride on but I am tempted to use my leftover car oil rarther than throw it out. .

Also can I use engine oil for 2 strokes ..we always used this in the Victa when I was a kid. ..the engine kept running normally.
My Father used the Victa for employment for a number of years ..I never heard of any issues ..{maybe it was falling apart inside and I was just not aware..?}

I must admit I used engine oil in my victa's current fuel supply because I had run out of 2 stroke oil ...seems to run ok although maybe a little more smoky than normal. I will revert back to 2 stroke oil on next refill of fuel all the same.

john2,

What you need to look at is in the old days with the Victa mowers you were using leaded fuel which was a lubricant for the cylinder and you could use engine oil instead of two stroke oil as recommended by Victa.

The fuel these days is not consistent in Australia and does not have a standard like the USA has.

People can argue all the time regarding oil and fuel but until such time that they are consistent nobody will win.

Thanx Bruce, best stick with what is currently recommended by the manufacturers ?

....now back to some other pressing PC problems I inherited from the Pine Rivers PC club here in Brisbane .

I just joined & have already been loaded up with jobs

I suggest you completely avoid using engine oil as the oil component of two-stroke fuel. I too remember the days when we used to have to do that, and I wouldn't want to return to them. The specific-purpose two-stroke oil does not separate from the petrol the way engine oil does, and in my experience it does not grow 'whiskers' across the spark plug gap at full throttle the way engine oil does.

In both two and four stroke mowers I suggest you just look in the manual for that specific mower, and do what the manufacturer recommends.

Yes it was BP Zoom, I never bought it, I prefer to mix my own.

I certainly recall when they had a green drum (about 20 gallons?) labelled BP Zoom in between the bowsers. The gas station proprietor poured in the right amount of BP's two-stroke oil and pumped in leaded gas to fill the drum. After that they drew the mixed fuel out from the stopcock at the bottom of the drum when somebody brought in their mower fuel can for filling. I think I even recall one gas station in the latter days of that system that had two of the dispenser-drums with different oil-to-petrol ratios.