Can I use 20w50 motor engine oil in my lawn mower?
The short answer is yes, you can use 20w50 oil in a lawnmower but results may vary.That's not the end of it, though.
This kind of oil is not designed specifically to be used in a lawnmower.
20W50 is actually a fairly specialized petrol engine oil formulated for use in engines made generally before 1980.
1980, that was forty odd years ago!
The starting point for considering what kind of oil to add is the characteristic of the oil known as viscosity. This is the thickness of the oil and that has a direct effect on how well the engine is lubricated during use, especially when temperatures change.
The starting point for considering what kind of oil to add is the characteristic of the oil known as viscosity. This is the thickness of the oil and that has a direct effect on how well the engine is lubricated during use, especially when temperatures change.
Typically, '30 weight oil' (often referred to as SAE30) is used in lawn mowers as it is designed with the engines of older lawn mower in mind - temperature factors are a key player here - both of the engine (which obviously heats differently from a car) and also the local weather conditions play a part in determining engine performance.
The thicker viscosity of 30 weight oil assists air-cooled engines to keep them running... cooler!
SAE30 is very suitable for older, aged engines to use.
20w50 will work in engines for what could be described as the summer weather period. If you live in colder climes then you should really consider using 30 weight.
If you live in a region that has large temperature swings between summer and winter then a blended oil such as 10w30 may be suitable - the 10w reflects the winter use protection and the 30 reflects the warm temp.
If you've spotted a trend in those numbers, good on you - the colder weather in which you use your engine, the lower your W for winter number can go.
One thing to bear in mind is while winter oils can help improve cold weather starting they may contribute to an increase in oil consumption by the engine. You just want to get your grass cut though eh?
When in doubt, you should always refer to the user manual of the lawn mower. If you do not have it, then google it - the manufacturers place them online because they know their users will benefit from them - a happy user is a happy brand whisper naturally!
Another factor to consider in your oil choice is will it help keep the engine clean internally?
Will the detergents contained in the oil help prevent sludge build up?
Most quality engine oils will have such detergents added - and for this reason alone, we recommend you avoid using cheap engine oil if you can!
There is an argument that you see creeping in every so often that the modern mower engine, is still basically the same kind of engine that has been around for 60 years since the end of the Second World War.
Those old & original engines ran on the crudest, rudest kind of oils around. The modern oils, including synthetics, are clearly superior oils and probably do over and above what is required for many engines. This train of thought probably underlies why many users report using certain oils in certain engines and never having any issues with the oil's performance.
Take that how you will!