Correct grade of engine oil query

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vron
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Hi everyone, can you help with this question please.

We have just bought a Mc Culloch Petrol Rotary Mower 46s 500 series.

It has a Briggs and Stratton Engine, and recommends using SAE30 oil, which we have bought.

As you know this is quite expensive to buy, can we use an alternative, like say 5w30, 10w30 or 20w50, without there being any risk of damaging the engine.

Our rotovater engine (Tecumseh 3.5) and our Qualcast Classic 45s petrol mower, both advise SAE 30 oil for the engines, but also says a multigrade oil of 15w40 or 20w50 is acceptable, we use the 20w50 in both, with no problems.

Your advice would be most appreciated.
Vron, Tara & Harley. (The black beastie)

"The more people I meet, the more I like my Dogs"
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Cider Boys
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Hello Vron

I am NOT an expert on oil, but belive me not many are.

If you are running the machine during its waranty period I would use whatever they advise.

Outside this period, my view is that if it quotes SAE30 then I would use 20W/50 Multigrade. I am not an expert either on small horticultural engines but have some experience of large vintage engines. Historically you could only buy straight mono mineral oil and SAE30 was a commonly recommended oil weight for engines with a lighter weight for Winter use and a heavier weight for summer use. Around the 1960s, multigrade oil was developed that allowed you to have the benefit of one oil that performed to specifications all the year round. Simply a 20W/50 gave you the equivalent of using a SAE20 in the Winter and behaved like a SAE50 in the summer. A small engine generally relies on a splash system of lubrication and I have found the thickness (at air temp) of 20W/50 to be the same as SAE30. however I would be quite happy to use a 15W/40 unless the engine was running in very hot conditions. I have restored and run many Vintage engines and always run them with modern mineral multigrades because they are far superior to the old straight monogrades. Why some classic vehicle owners pay over the top prices for oils that were recommended when modern superior oils were not available beats me. Perhaps they have improved straight oils now and they have an API rating but I doubt it. Whatever oil you use change it at the recommended times and keep the air filter clean.

I repeat that I am not an expert and welcome other opinions particularly Clive's who has much knowledge of small engines.
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Geoff
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I use Focus Do It All own brand SAE30 which isn't particularly expensive. One year I recorded my mowing times and found in one season I was well within the suggested hours between changes. As top ups during the season don't amount to much the volume used with an annual change isn't great, for a 12½HP B&S. I wouldn't get rich swapping to 20/50.
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Clive.
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Hello,
I go with the SAE30 recomendation in the machines at work...In fact we use the B&S own brand red coloured SAE30 which seems to be some genuinely good stuff..

...but at home I have tended to use SAE20w50..as a good alternative.

If in warranty though go with what is recomended...SAE30.


10w30 and 10w40....is good for things Honda but are a bit too "thin" I reckon for others..

Clive.
madasafish
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I have been successfully using either 10-40 engine oil or Tesco's SAE30 (bought dirt cheap) for the past 28 years. My Mowers have minimal engine wear and I am still running a 1973 Hayter....

Modern semi synthetic oils are probably far better than is really required..
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