Is Mobil 1 0W40 shear stabile enough for a splash lubed generator?

Joined
Mar 31, 2010
Messages
6,592
Location
Iowa
I'm helping my neighbor up the road get his generator program up to speed after he was caught unprepared this winter. It's a Centurion 5kw that is brand new except for a few hours from this winter.. I'm going to check the valve clearance, replace the spark plug with a 5/8" hex NGK for ease of removal, replace the broken gas valve (the reason he was unprepared), check the engine speed for proper frequency and change the oil several times to get the metal from break-in out.. This unit will need to be able to be started and ran any time of the year, but the most likely time will be summer. I was thinking M1 0w40 or maybe 5w40 to cover the temp extremes that it can see (from as cold as -20F (rare) to 100F). Realistically the coldest would be about 0F to 90F.
 
This is what your manual says..

oil.webp
 
For 0f starts you need a 0 bottom number. No way I could pull start my 5600w 8k surge BS in the single temp. numbers with a 5-30w oil in it. Its manual read the same 5-30w language.
I would lift the gen. set off the ground with the recoil and it would not spin over fast enough to start. That unit was not stored in a warm area either.
 
I have 5w30 in the snow blower and the 6.5K Predator. It rarely gets below 10f here anymore. I keep a couple qts of 20W50 for the genset figuring that I could put that in during a re-fuel. If you check oil, you should be able to stay ahead of any loss. IIRC, both engines have a low oil shutoffs...
 
Red Line High-Performance 5W-30 Motor Oil has a pour point of -45ºC (-49ºF) and about the highest HTHS around for any 5W-30. Most synthetic 5W-30's have an HTHS around 3.0 to 3.1. Air cooled engines, when running hot, such as heavily loaded during summertime, really prefer an HTHS over 3.5, and 3.8 might be considered best.

Rotella T6 5W-40 has a pour point of -51C and HTHS of 3.9 to 4.0 (according to my searches) and might be a great all around choice.
 
My main concern about RT6 5w40 is my neighbor being able to pull the engine over in 0 degree weather. Otherwise I'd certainly prefer it with its higher HT/HS over Mobil 1 0w40
 
Back
Top Bottom