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Old 08-24-2010, 04:35 PM   #1
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Onan 7.5 generator and anti-freeze sca

Have followed all the discussion concerning the engine and the "forever" anti-freeze where SCA is not used. Purchased 10 gal. of Peak Global Lifetime anti-freeze and the "blank" filter (no SCA) today. Also all the filters for the above generator. See it coming don't you? Wonder if the Onan generator water filter has SCA in it as I also plan on using the "forever" anti-freeze here

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Old 08-24-2010, 05:10 PM   #2
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I believe I am correct is stating that the 7.5 diesel Onan uses ethylene glycol anti-freeze. I don't know if the "forever" version is recommended in the Onan. You should call Cummins for some good info.

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Old 08-24-2010, 05:27 PM   #3
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I was just talking to Fleetguard this morning to get a part number for my ISL coolant extender which is a n OAT coolant. I just checked the coolant in my Onan 7.5 and it's a different color(green). According to my Onan manual it just says to use a ethylene glycol 50/50 coolant mixture. I'm not sure if the generator needs the SCA'S or the OAT coolant since it's only applicable to wet sleeves engines and I don't know if the generator has sleeves but I guess putting in the OAT coolant would be less maintenance than the SCA . The OAT coolant is ethylene glycol.
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Old 08-25-2010, 06:14 AM   #4
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SORRY, I purchased so many filters yesterday that I could swear there was a "water" filter for the generator. There isn't! So, that answers the question. Also the Peak Global is an eth. gly. based anti-freeze so it adheres to Onan specs.............
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Old 08-27-2010, 08:09 AM   #5
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Unlike your RV's engine, the Onan generator's engine is not wet sleeved. Therefore it does not need any SCAs. Just about anything will do as far as antifreeze is concerned. And yes, you are right, there is no filter on the Onan.

Some of the older Onans came with basic "green stuff" heavy duty antifreeze. My '04 Bus came with that. My '07 Bus came with Fleetguard's ES Compleat (blue stuff) antifreeze.

I have replaced it with and OAT coolant. The OAT coolants are extended life and feature Organic Acid Technology. In a Cummins engine this negates the need to check SCA levels and the coolant is good for 6 years with an extender added at 3 years. It's great stuff.

Your Onan doesn't "need" OAT coolant or anything with SCAs. However, it will benefit from it. Fior one thing you won't need two different coolants because the same thing that's in the Cummins can be in the Onan. Secondly, OAT coolants do not attack aluminum like non-OAT coolants do. There's lots of aluminum in your Onan so you'll gain some benefit there.

For more details check out RVcruzer.com - Coolants for HD Diesel Engines in RVs.
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Old 08-31-2010, 02:58 PM   #6
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Assuming you carry extra Fleetguard "Complete" for the coach it will be just fine in the diesel genset. You can check your owner’s manual, but I talked to Cummins (who owns Onan) and they said the same stuff in the big engine will work fine in the genset. No since in carrying two different types and get them confused when needing to add coolant to the coach engine. The complete is for diesel engines only and Cummins specifically, if you have a CAT diesel, you need to check with cat to see what they want you to use.

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