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CARVAL Motorsports · 09-07-2008, 06:42 PM

Changed oil on the Chevy 7.4 and the Generac yesterday. I have about 68000 on the Chevy and 480 hours on the Generac. I used Valvolene Full Synthetic for both applications, 10w30. After completing the task, I have been wondering if I should have just stuck with Regular oil for the generator. Opinions on this?

CARVAL Motorsports · 09-07-2008, 06:42 PM

Changed oil on the Chevy 7.4 and the Generac yesterday. I have about 68000 on the Chevy and 480 hours on the Generac. I used Valvolene Full Synthetic for both applications, 10w30. After completing the task, I have been wondering if I should have just stuck with Regular oil for the generator. Opinions on this?

CARVAL Motorsports · 09-07-2008, 06:44 PM

BTW, we use the Generator a lot during our at-track weekends. Sometimes all night to.

Jay W · 09-07-2008, 07:39 PM

Carl, IMO the high heat environment of an air cooled generator is good fit for Synthetic oil. Your genny will do just fine on either Dinno or Synthetic. IMO Synthetic adds a little extra heat protection.

I used Synthetic in my previous 7.4 L 94 Itasca / 5.5 Onan genny. I however do not use Synthetic in my DP.

PaulC · 09-08-2008, 02:17 AM

When I had our Onan 7000kw generator serviced the factory authorized service center did NOT recommend synthetic oil for Onan generators.
Paul

JoeT · 09-08-2008, 04:22 AM

You might check you manual to see if it mentions synthetic. The Onan manual for HDKAL, AQ, AR, and AS models say "do not use synthetic oil". However, the manual for HDKAJ does not mention synthetic at all.
I don't use synthetic in my Onan HDKAJ. I don't feel the benefits, if any, outweigh the cost.

FrontRangeRVer · 09-08-2008, 06:03 AM

We use Mobil 1 20w-50 in our Onan 5500....Synthetic oil is GREAT for air cooled engines.

Edw · 09-08-2008, 04:08 PM

I spoke with Generac about some issues on my 5500, 1999 model. I believe I Was told not to use special oils or additives as the air cooled engine has special requirements. Call Generac. They were very happy to help and discuss proper operation.

exrench · 09-08-2008, 04:33 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Edw:
I spoke with Generac about some issues on my 5500, 1999 model. I believe I Was told not to use special oils or additives as the air cooled engine has special requirements. Call Generac. They were very happy to help and discuss proper operation. </div></BLOCKQUOTE>
They were correct to say the "air cooled engine has special requirements"and synthetic oils are very suited to those needs.

dmzkiller · 10-17-2008, 09:43 PM

If you look at the 'offical' Onan generator oil, its just 15/40.....I used the left over cheap Walmart brand that I had left over. I can't believe Camping World gets 100 bucks to 'service' a generator..........thats easy!

SCVJeff · 10-19-2008, 12:43 AM

Seems to me that if the API standard is met, anything above that, including synthetic is a plus and pretty hard to argue from the manufacturer building and rating their equipment against these standards.

David K · 10-25-2008, 11:43 AM

I am not saying to change back to dino oil but, if you do a search on this forum about generators starting and then shutting down after a short run, you will find that some of them do not like the synthetic oil as it does not have enough viscosity to let the engine know that it is full of oil. People have switched out to the synthetic oil product and then after experiencing problems, they changed back to dino and the run problem went away. I am just posting this so you can be aware that synthetic can cause run problems -- if you start to experience these problems, the first thing you might want to do is to switch back to the 15 - 40 dino oil.

SCVJeff · 10-25-2008, 10:00 PM

Someone way smarter than me needs to explain how that is. Viscosity is clearly listed on either flavor of oil and must adhere to API standards.

Steve Rankin · 10-26-2008, 10:39 AM

We use synthetic oils in almost everything. Our cars & trucks engines, transmissions and differentials. We also used synthetics in our air cooled Onan 6.3 generator as well as our air cooled garden tractor. Air cooled engines tend to have more heat-related issues than liquid-cooled engines and the synthetics are ideal for that.