OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines Oil

I think I read somewhere that in a pinch, you can use 4 stroke engine oil in a 2 stroke engine. But can you use car oil in place of 4 stroke mower oil?

Oils aint oils Allan but Ive done it before.

Mowing a mates block a few days ago I checked the oil level on a B&S 3.5 only to find it near dry.

I popped 500 ml of Magnatec diesel (15w40)into the thing as it was a 40 k drive home to get the B&S oil and she ran fine although the high detergent of a diesel oil is a concern.

As for engine oil as 2 stroke?

Did it years ago on a motorbike when the 2 stroke injection system packed in and she was ok for a day or so but much worse for wear after day 2 so id think not

Some say you should run one particular oil in 4 stroke mowers. Personally by the time a lot of mowers get their first oil change, anything is better than that thick black gluggy sooty Poo in the sump.

I generally use the left over oil from my cars oil changes, being either magnatec from Kirstins car or shell helix left over from the datsun.

LOL - that's what I had in mind actually, because I always have oil left over from car oil changes, AND I just switched to using Magnatec.

Thanks.

The reason I asked was... I went to a Bunnings information session years ago on how to service your mower. The guy said to some lady there that 4 stroke oil was just the same as car oil. He was hinting if the car oil they used was cheaper than 4 stroke, they could just use the car oil instead. (And the 2 stroke thing.)

Come to think of it, he was talking about synthetic oil - because I remember now he said you could use it as 2 stroke oil, but it would be expensive.

not only that motor oil is much harder to mix with the fuel than 2 stroke oil.

left over car oil?

Sheesh lol

For the half litre or so Id use new stuff

Hi to All, fellas, this thread has been discussed recently sprinkled with debate and is worth re-visiting; see Gomowers post #12441 "Engine Oil for 4 Stroke Mowers" with a final post by grumpy which says, quote:
"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." unquote.
This would be my recommendation as well.

Joe, during its working life oil gradually acquires suspended dirt, grit, and metal fragments. Oil filters limit the size of particle that is allowed to recirculate in the system, but four stroke mower engines seldom have filters. If you put oil that is already carrying a maximum load of suspended crud into a four stroke mower, you might as well leave the old oil in there. Perhaps the greatest benefit from changing oil in a mower is getting rid of the old load of suspended crud and starting off clean. (In a car engine the biggest benefit from changing oil is getting a new supply of detergents and other additives, but mower engines need new oil every 25 hours - cars engines, with their filters, mostly only need oil changes every 15,000 km). I think you'll get longer life from your mowers - many of them rare collectors' items - if you feed them new clean engine oil at regular intervals.

I am talking about the left over oil from refilling the car. Since I usually buy 5L bottles, From the 01 corolla I get about 1.5l left over and the datsun (L18 engine) I get about a litre

However I have been known to use the sump oil from the corolla, The oil from the car after 10000km comes out slightly darker than when it went in (like golden syrup than honey)

A lot of the very sad briggs motors I have come accross over the years the oil is like molasses, so thick that it can take up to an hour to get most of it out, and then you still have to rinse the crankcase with diesel to get the rest of the crud out of there. Then the effort to wash that "muck that might as well be tar or black axle grease" to wash off your hands is another story.

Funny thing is though, with this old thick stuff running in the system, old briggs engines don't smoke at all and seem to run fine, once they have fresh oil in them though, they can sometimes start smoking a little as the new oil is a lot thinner.

One day we should have the competition "who can find the most neglected engine that still runs " :p

If you let stationary engine and antique tractor collectors join the competition, the mower guys won't get a look-in. Some of the experienced tractor guys walk up to old tractors that have been out in the paddock abandoned for more than 50 years, get them started in 10 minutes to an hour, and drive them onto a trailer. The trick is to let the water out of the bottom of the sump without letting the oil out. You probably want to let it warm up a bit on that old oil then drain it out, so it will take some crud with it. That way you can run it for longer on that first lot of new oil (not long, but longer).
Warning: do not do this kind of thing with old racing engines that may have run with castor oil as lubricant. Major disaster may result. I recall somebody who I won't name destroying the engine of a borrowed Maserati 300S that way. The castor oil leaves a varnish on the crankshaft bearings and in the cylinder bores. When the engine warms up sufficiently the varnish partly melts and if it is mixed with mineral oil it acts like instant superglue. If you are in the middle of doing a few demo laps on race day at Sandown at the time, it can end badly.

BTW, I agree with you that if the used car-engine oil is still clear, it should be good enough for the mower so long as you change it regularly in the mower. The main enemy is suspended stuff in the oil, and that pretty much always affects its clarity. However clear is not the same as 'I can still see some daylight through it if I hold it up to the sun'.

Yes, I bought several 5L bottles of Magnatec from Repco on sale, including free oil filter. The car takes 3.8L, so there's around 1L left over. I rarely top up the engine again before the next oil change. So you end up opening a new bottle and then you have 2L left. And 3L the time after that. So you have to open three 5L bottles before you have no open oil.

Whereas from the 4 stroke mower point of view - a 4L bottle sits in my shed for months. So I thought, if car oil is basically the same as 4 stroke oil...

I read in that other thread grumpy giving a good argument for using car oil as 4 stroke. Using it to mix 2 stroke is now out, but was there a verdict about car oil as 4 stroke? (I keep thinking if anything, car oil would be too good for the job and therefore ok.)