Can i use lawn mower oil in car engine?

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Dec 26, 2005
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Hi, sorry if this is a dumb question,
but is it safe and ok to use four stroke lawn mower or garden oil in car engine?
My engine calls for at least API SG oil,
and Mobil and Castrol has Lawn mower/Garden oil that has API SG and SJ/SL specs, and in my town those oils are half the price of regular motor oils.
My other option would be Liqui Moly 10w30 touring high tech, but it has the SF spec, and i'd need the SG spec at least?

Its getting quite hard to find mineral oils these days that are 5w30 or 10w30, but the Mobil 4 stroke lawn mower oil is as far as i can tell, mineral based, and cheap.
But is it safe to use in 90's GM car?
 
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The short answer is...It's not optimal.
Newer oils today that are API SP GF-6A are all backward compatible to any oil(s) that came before them. And waaaaaay BETTER!
Just because your older vehicle/engine call for an older spec, doesn't mean that we need to go searching for those older specs.

For example:
The Firebird in my signature with its OE engine, in the Owner's Manual(which isn't going to magically change its wording), it calls for SE/SF. But that doesn't mean that this is the oil that I should be looking for. I have always used the newest oils that have come to market.

Those older oils don't hold a candle to todays oils.
 
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I'm curious where you're finding mower oil for half the price of automotive engine oil. Unless you're comparing a 20 ounce bottle of mower oil to a 32 ounce bottle of automotive engine oil, I just don't see that sort of price variation where I live.

API SG is an obsolete specification. Go to WalMart and buy their brand of your specified viscosity. It's usually difficult to beat the price unless you find some close-out somewhere.
 
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Its getting quite hard to find mineral oils these days that are 5w30 or 10w30, but the Mobil 4 stroke lawn mower oil is as far as i can tell, mineral based, and cheap.
But is it safe to use in 90's GM car?
Why the need for conventional oil? is there a fear of oil leaks?
 

Carguy80

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The short answer is...It's not optimal.
Newer oils today that are API SP GF-6A are all backward compatible to any oil(s) that came before them. And waaaaaay BETTER!
Just because your older vehicle/engine call for an older spec, doesn't mean that we need to go searching for those older specs.

For example:
The Firebird in my signature with its OE engine, in the Owner's Manual(which isn't going to magically change its wording), it calls for SE/SF. But that doesn't mean that this is the oil that I should be looking for. I have always used the newest oils that have come to market.

Those older oils don't hold a candle to todays oils.

Thanks for the reply.
Im just curious about garden oils, since they at least cover the specs for my application
and are cheap, so i have been wondering that are garden oils the same as automotive oils.
I do not wish to damage my engine if i were to put garden oil or lawn mower oil in the engine, if the oils are not somewhat the same.

I have been looking for a cheap conventional oil, and it just frustrates me since i can't find for example Mobil conventional oil from my area unless its some garden oil, but if its the same as car oil with just a lawn mower picture on the bottle,
i wouldn't mind.
 
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Carguy80

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I'm curious where you're finding mower oil for half the price of automotive engine oil. Unless you're comparing a 20 ounce bottle of mower oil to a 32 ounce bottle of automotive engine oil, I just don't see that sort of price variation where I live.

API SG is an obsolete specification. Go to WalMart and buy their brand of your specified viscosity. It's usually difficult to beat the price unless you find some close-out somewhere.

Im in Europe. I saw one liter bottle of Mobil garden oil for about 10 euros, which is cheap, since usually in my area oil usually costs almost twice as that, depending if its a full synth or not.
 
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The reason that it's becoming difficult to find plain Jane conventional oil is because modern oil specifications are very strict and difficult to meet. The days of blending a group I solvent refined oil with some detergent and metallic ash are over. Oil blenders need to meet the requirements of modern vehicles and to do so the formulations to pass modern testing has become more difficult. It takes a much more robust additive package and a more stable base fluid to carry current API ratings so they are blending group II and group III base stocks in the cheapest product. They capitalize on this by advertising the product as a synthetic blend to make it sound more impressive. The fact is that the products are blended to meet minimum standards but they are needing to use "synthetic" basestock to achieve this.

The beauty is that the bar for today's minimum standards is set pretty high. Modern oils, even the cheapy no-name stuff, is high quality if it carries the API donut.
 
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Im in Europe.
Well there's a tidbit of valuable information. Post some bottle pictures and prices of what you're looking at so we can join the search. What part of Europe are you in?

If this is for a Russian artillery gun in Ukraine then all bets are off :)
 
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Yes, im afraid the engine might leak since its a car from the 90's. Other problem is the cost of oil. Mineral oil is usually the cheapest.
What’s cheaper, oil or a replacement engine? Run the better stuff, not expensive mind you, but something that is the proper spec.

Synthetic doesn’t cause leaks, worn gaskets and seals do.
 

Carguy80

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Well there's a tidbit of valuable information. Post some bottle pictures and prices of what you're looking at so we can join the search. What part of Europe are you in?

If this is for a Russian artillery gun in Ukraine then all bets are off :)
So far i've been looking what i can find online, Mobil and Castrol garden oil were the cheapest. Im in Sweden.
Most mineral oils around here are either 10w40 or 15w40.
I've also searched online, UK and Germany, most what i can find are blends, but so far the Mobil 4 stroke garden oil is what might be suitable, it is mineral based, 10w30, and has the minimum specs required for my application which is SG.
 

Carguy80

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What’s cheaper, oil or a replacement engine? Run the better stuff, not expensive mind you, but something that is the proper spec.

Synthetic doesn’t cause leaks, worn gaskets and seals do.

Here is info of the Mobil garden oil that i have been thinking. It says it meets the SJ spec, so for an engine requiring at least SG, i think that might work, but im not sure since its "garden" oil. 🤔
 
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I'm curious where you're finding mower oil for half the price of automotive engine oil. Unless you're comparing a 20 ounce bottle of mower oil to a 32 ounce bottle of automotive engine oil

I think that's what is going on. They sell the 20oz bottle for a bit less (but more costly per quart) for convenience. Even dollar general has 20oz bottles of regular oil.
 

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The reason that it's becoming difficult to find plain Jane conventional oil is because modern oil specifications are very strict and difficult to meet. The days of blending a group I solvent refined oil with some detergent and metallic ash are over. Oil blenders need to meet the requirements of modern vehicles and to do so the formulations to pass modern testing has become more difficult. It takes a much more robust additive package and a more stable base fluid to carry current API ratings so they are blending group II and group III base stocks in the cheapest product. They capitalize on this by advertising the product as a synthetic blend to make it sound more impressive. The fact is that the products are blended to meet minimum standards but they are needing to use "synthetic" basestock to achieve this.

The beauty is that the bar for today's minimum standards is set pretty high. Modern oils, even the cheapy no-name stuff, is high quality if it carries the API donut.
Yep - and the vertical co’s are better off making less base stock “flavors” - enter EHC and similar Grp2+
 

Carguy80

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It claims to meet API SJ so I'd go for it.
Thanks. I might. Im most certainly tempted, mostly because of the cost, and because if its mineral based. Sometimes i think old school cars need old school motor oils,
not that new oils would not be better, but i think that in my application, the engine might be happier with old school type of oil, since its an old push rod engine without todays variable valve timing and all that.
I think even some universal tractor oil might work, and the engine would be none the wiser, other than it might just leak if i were to put todays synthetic oil in it which keep engines clean, and for an old engine, perhaps too clean 😄
 

Carguy80

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Of all the things you shouldn’t do to an engine this is the thing you probably shouldn’t do the most.
You mean its not a good idea to use garden oil? Are garden oils the same as automotive oils or are they different? Additive wise and so forth.
 
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It's from Exxon-Mobil, it should be a plenty "good enough product". Its likely not far off from any of the ACEA A3, B4 Techno-Synthese products using quality group II base oils with a strong EP AW package.

I actually wish I could find something like this in the States, as the go to Shell Rotella Triple protect 10W30 has dissappeared from strores around me. It is likely renamed and available in drums Stateside
 
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