aunut Posted March 6, 2015 Report Share Posted March 6, 2015 Changing my new Onan 5500 gas Genset for the first time. The specs say 30W, 10W30 or 15W40. 15W/40 is hard to find for a gasser. Can I just use 10W/40? Link to comment Share on other sites More sharing options...
jc2 Posted March 6, 2015 Report Share Posted March 6, 2015 Our previous mh had the Cummins-Onan 7000 gas genie and we used 15w/40 Rotella or Tech 2000. Both available at Walmart. Cummins can get kind of picky if you don't use the recommended oil weights and a problems were to occur. Link to comment Share on other sites More sharing options...
Ray,IN Posted March 6, 2015 Report Share Posted March 6, 2015 There is no reason you cannot use 15W40 diesel oil in a gas engine. The main difference is, diesel oil has more additives to keep contaminants in suspension than oil for gas engines-and of course the weight designation. Link to comment Share on other sites More sharing options...
skp51443 Posted March 7, 2015 Report Share Posted March 7, 2015 Does Onan give you any service categories in addition to the weight? http://www.api.org/certification-programs/engine-oil-diesel-exhaust-fluid/service-categories Link to comment Share on other sites More sharing options...
aunut Posted March 7, 2015 Author Report Share Posted March 7, 2015 Does Onan give you any service categories in addition to the weight? http://www.api.org/certification-programs/engine-oil-diesel-exhaust-fluid/service-categories Just the temp ranges each would cover. Link to comment Share on other sites More sharing options...
Pat & Pete Posted March 7, 2015 Report Share Posted March 7, 2015 Our Onan operator's manual simply recommends using an oil with an API rating of SF . No particular weight of oil other than what the chart of weight to temperature has . Here is that chart . Note that it includes 15W40 . I have used diesel oil in gas motors with no ill effects . Link to comment Share on other sites More sharing options...
skp51443 Posted March 7, 2015 Report Share Posted March 7, 2015 I'd say then that any oil that meets or exceeds the SF rating (SF SG SH SJ SL SM SN) and matches the temp range expected is going to be fine. I'd look for a GF-5 and SN rated oil as it is the latest spec for gas engines according to the PDF I linked above. Link to comment Share on other sites More sharing options...
aunut Posted March 7, 2015 Author Report Share Posted March 7, 2015 Our Onan operator's manual simply recommends using an oil with an API rating of SF . No particular weight of oil other than what the chart of weight to temperature has . Here is that chart . Note that it includes 15W40 . I have used diesel oil in gas motors with no ill effects . Looks like I do need 15w40 It gets pretty hot down here. But, I don't understand why 10w30 and 10w40 have the exact same ranges. Link to comment Share on other sites More sharing options...
Pat & Pete Posted March 7, 2015 Report Share Posted March 7, 2015 But, I don't understand why 10w30 and 10w40 have the exact same ranges. Probably because they are so close in differences as to not make much difference . Hopefully that made some sense . Link to comment Share on other sites More sharing options...
kathydavidb Posted March 7, 2015 Report Share Posted March 7, 2015 Our previous mh had the Cummins-Onan 7000 gas genie and we used 15w/40 Rotella or Tech 2000. Both available at Walmart. Cummins can get kind of picky if you don't use the recommended oil weights and a problems were to occur. The Rotella 15w/40 from Wal-Mart is what I've used on my Onan 5500. If you're picky you can purchase Onan's brand oil at either an Onan repair facility or Camping World. The choice is yours. Dave. Link to comment Share on other sites More sharing options...
AlCherry Posted March 7, 2015 Report Share Posted March 7, 2015 Oil topics are dangerous, but I'll throw in. I use Mobil 1 V-Twin, formulated for air cooled motors. It is a 20w50. It is available at Walmart in the motorcycle section. Link to comment Share on other sites More sharing options...
Biker56 Posted March 7, 2015 Report Share Posted March 7, 2015 I have used the 20w50 for air cooled motorcycle oil in my 6.5 for the last 13 years. After all the Onan is air cooled except the diesel ones. Link to comment Share on other sites More sharing options...
jayco1 Posted March 8, 2015 Report Share Posted March 8, 2015 Can't beat Rotella T, and is available almost everywhere. Link to comment Share on other sites More sharing options...
aunut Posted March 8, 2015 Author Report Share Posted March 8, 2015 The Rotella 15w/40 from Wal-Mart is what I've used on my Onan 5500. If you're picky you can purchase Onan's brand oil at either an Onan repair facility or Camping World. The choice is yours. Dave. I assume tht Rotella is made for diesels. But, according to other posts, it shouldn't matter? Link to comment Share on other sites More sharing options...
skp51443 Posted March 8, 2015 Report Share Posted March 8, 2015 The diesel API stuff shouldn't be an issue as long as the required SH rating is met or exceeded. You need to consult the charts to make sure of that unless it is marked on the can or jug. Link to comment Share on other sites More sharing options...
kathydavidb Posted March 9, 2015 Report Share Posted March 9, 2015 It sounds like you want the best for your generator with out getting the wrong oil. Why don't you then get the Onan brand oil from an Onan repair facility or from Camping World? Then you have peace of mind. It will be costly but I think you only need 2 qts. so it isn't that much more. Dave. Link to comment Share on other sites More sharing options...
aunut Posted March 9, 2015 Author Report Share Posted March 9, 2015 It sounds like you want the best for your generator with out getting the wrong oil. Why don't you then get the Onan brand oil from an Onan repair facility or from Camping World? Then you have peace of mind. It will be costly but I think you only need 2 qts. so it isn't that much more. Dave. You're exactly right. It's about a 50 mile round trip, but I think I'll bite the bullet. Link to comment Share on other sites More sharing options...
skp51443 Posted March 9, 2015 Report Share Posted March 9, 2015 A fifty mile drive each way when Amazon has it? http://smile.amazon.com/Cummins-3265336-Onan-SAE-15W-40/dp/B00278MET8/ref=sr_1_1?ie=UTF8&qid=1425868461&sr=8-1&keywords=onan+oil http://smile.amazon.com/MOTORHOME-TRAILER-AUTOMOTIVE-ENGINE-ONAN/dp/B000BRJV5W/ref=sr_1_3?ie=UTF8&qid=1425868461&sr=8-3&keywords=onan+oil All said, dinosaur oil is pretty much dinosaur oil as long as the weight and APIs match or exceed your needs so I'd just buy something locally that meets your requirements. Link to comment Share on other sites More sharing options...
mscans Posted March 9, 2015 Report Share Posted March 9, 2015 A fifty mile drive each way when Amazon has it? http://smile.amazon.com/Cummins-3265336-Onan-SAE-15W-40/dp/B00278MET8/ref=sr_1_1?ie=UTF8&qid=1425868461&sr=8-1&keywords=onan+oil http://smile.amazon.com/MOTORHOME-TRAILER-AUTOMOTIVE-ENGINE-ONAN/dp/B000BRJV5W/ref=sr_1_3?ie=UTF8&qid=1425868461&sr=8-3&keywords=onan+oil All said, dinosaur oil is pretty much dinosaur oil as long as the weight and APIs match or exceed your needs so I'd just buy something locally that meets your requirements. Stan, You bring up a good point. Does the gen. manufacturer recommend or disallow synthetics? When I bought my Honda 2000i the dealer filled it with synthetic and that is what I have used since. Link to comment Share on other sites More sharing options...
Pat & Pete Posted March 9, 2015 Report Share Posted March 9, 2015 A fifty mile drive each way when Amazon has it? http://smile.amazon.com/Cummins-3265336-Onan-SAE-15W-40/dp/B00278MET8/ref=sr_1_1?ie=UTF8&qid=1425868461&sr=8-1&keywords=onan+oil http://smile.amazon.com/MOTORHOME-TRAILER-AUTOMOTIVE-ENGINE-ONAN/dp/B000BRJV5W/ref=sr_1_3?ie=UTF8&qid=1425868461&sr=8-3&keywords=onan+oil All said, dinosaur oil is pretty much dinosaur oil as long as the weight and APIs match or exceed your needs so I'd just buy something locally that meets your requirements. Seems a better deal here : http://www.pplmotorhomes.com/parts/onan-generators/onamax.htm I use the proper weight and rated dino oil in our Onan . Never a problem . It has a touch less than 800 hours on it . Link to comment Share on other sites More sharing options...
skp51443 Posted March 9, 2015 Report Share Posted March 9, 2015 Usually the manufacturer just ignores the synthetic issue unless they require it (for real or marketing reasons) and just give weights and API requirements. I'm sure it is available cheaper many places, I just use Amazon as my default place to look for stuff I'll never buy because it confuses the heck out of their ad system. :-) Link to comment Share on other sites More sharing options...
kathydavidb Posted March 9, 2015 Report Share Posted March 9, 2015 Stan brought up a good point. I also ordered my oil & filter from amazon. At the time gas was $3.50 a gal. & I would have to drive 70 mi. each way to get the oil& filter. So, it was actually cheaper to order it on line & have it sent to me in a couple of days. Now I keep a spare filter on board. Dave. Link to comment Share on other sites More sharing options...
bobsallyh Posted March 9, 2015 Report Share Posted March 9, 2015 I also have used Shell Rotela 15/40 in our Onan Marquis Gold 7000 since 2004. Link to comment Share on other sites More sharing options...
AlCherry Posted March 10, 2015 Report Share Posted March 10, 2015 Stan, You bring up a good point. Does the gen. manufacturer recommend or disallow synthetics? When I bought my Honda 2000i the dealer filled it with synthetic and that is what I have used since. I did talk with Onan about synthetic oil. They said yes, but maintain service intervals. Link to comment Share on other sites More sharing options...
HighwayRanger Posted March 15, 2015 Report Share Posted March 15, 2015 I'm a fan of using synthetic oil and changing it annually. With less than 2 quarts needed, the price is no factor. But I do the same for my motorhome Triton V-10 as well, so......... I don't think you can necessarily equate "Onan" oil with "the best" oil. It is what they can buy at the lowest price, and I'm sure it's made for their label by some big-name company. When in doubt, get some Mobil 1 at Wally World and off you go! Roy Link to comment Share on other sites More sharing options...
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