lawnmower wants 15w40. can i use 20w40?

Forums › Home Workshop DIY › lawnmower wants 15w40. can i use 20w40?

Batman

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#269706 3-Apr-2020 14:51

before i practice my she'll be right maybe i should ask around. my modern as hyundai lawnmower wants 15w40 oil. i can't go out and buy it but i have 20w40 synthetic oil from the warehouse "good for older vehicles".

can i just use the 20w40 oil? the winter weight is higher so presumably harder to start - but ... yeah happy to take criticisms!

found link for the oil i have https://www.thewarehouse.co.nz/p/caltex-havoline-sae-20w-40-sf-engine-oil-4l/R2189282.html

RunningMan

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#2453860 3-Apr-2020 15:21

It will be slightly thicker before the engine is warmed up, so initial flow at startup will be a little slower which is when a lot of engine wear can happen. Given the W rating is measured at 0 Fahrenheit, and most of NZ is well above that temp at the moment it probably isn't quite as critical as in a cooler climate.

If it's just topping up the existing oil level it should be fine, but if it's a complete oil change it might may to contact the manufacturer first as sometimes a very specific grade is specified because of some previous problem with a type of engine.

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#2453869 3-Apr-2020 15:26

Yes will be fine the main thing is not to mix semi synthetic with fully synthetic

gbwelly

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#2454014 3-Apr-2020 18:23

Linux: Yes will be fine the main thing is not to mix semi synthetic with fully synthetic

Serious question, why is that?

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#2454155 4-Apr-2020 08:19

Possibly pick some up from your local petrol station next time you visit the supermarket?

Looks like supercheap is open to do home deliveries, oil is an essential item :-)

Batman

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#2454161 4-Apr-2020 08:34

Well just had a thought if thinner W is easier to start why don't I use shell helix ultra 0w40 f1?

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#2454169 4-Apr-2020 08:55

Batman: Well just had a thought if thinner W is easier to start why don't I use shell helix ultra 0w40 f1?

Your lawn mower aint gonna be sporting super high quality internal parts (piston etc)

Dont do it.

The local servo will have what you need. (any nearby that also have a workshop? They will have a better range).

Jase2985

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#2454170 4-Apr-2020 08:58

honestly just just what you have in the garage

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#2454172 4-Apr-2020 09:00

I was pitting 20/40 in my lawnmower and it was burning oil like crazy.

After having a service and the correct oil it did not burn anyware near as much.

The local service station will have it and they will be open, just contactless. You might have to get it via the nightpay.

John

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#2454228 4-Apr-2020 11:01

20w-40 in a motor specc'd for a straight 30 oil might burn more but the rings are probably tired anyway. Worldwide the Briggs & Statton recommended oil seems to flip flop between straight sae 30 and multigrade. I doubt that there is any difference in the engines. I wouldn't treat a lawnmower like a princess, it's not a 10,000 rpm Honda 50. It's probably much more important to have enough oil as most engines still rely on splash lubrication.

dolsen

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#2454247 4-Apr-2020 11:59

https://www.supercheapauto.co.nz/p/chief-chief-cheyenne-engine-oil---15w-40-1-litre/344486.html

$15 delivered.

Jase2985

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#2454383 4-Apr-2020 13:50

i always just used to use old engine oil in mine.

TwoSeven

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#2454402 4-Apr-2020 14:15

I thing a 20 weight might be a bit viscous for the winter. If it were a newish lawnmower, Id go with recommended.

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kotuku4

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#2454404 4-Apr-2020 14:17

Trade tested sell these mowers, and correct sync oil. 1 litre $15 delivered.

These are overhead valve engines, and you should run the recommended oil. The oil you have, is unlikely to cause issues short term.

Not to be confused with old flat head/side valve Briggs and Stratton engines that run straight 30w.