Onan generator oil

[booster]

Originally Posted by @Michael

Valvoline makes a 15w-40 SJ oil, but it's also diesel rated. Other than the OnaMax OEM oil I'm not finding SJ rated 15w-40 that is not also diesel rated.

AFAIK Redline doesn't have 15w-40 Powersports oil.

Next time I'll buy OnaMax and call it a day. I only run it an hour a month anyway - just to keep it from gumming up.

Redline does not have one in 15-40 but with the wide viscosity index the 10-40 covers it easily.


For a really, and I do mean really, good semi synthetic oil you may want to consider this Brad Penn oil in 15-40.

https://penngrade1.com/products/high...il-sae-15w-40/


Brad Penn is a favorite of the roundy round racers around here in the midwest and they claim it saves more engine life than any other oil in that application. They still use Pennsylvania spec basestock, which is said to have better properties than the world sourced oils, and a very robust additive package. I had this oil in our lawn tractor during a catastrophic chain of error and fate. I was mowing our swamp edge, which I do once a year in the fall, so big tall weeds and brush with intermixed cattails. Cattail fuzz sucked into the lower engine vents and plugged the air cooling to the engine. It got very sluggish and nearly stopped from overheat. I immediately got it into my shop and the oil was black and thickened badly so I figured engine was toast (a very good Kawasaki in a John Deere). Long story short, I pulled the engine and it had no internal damage at all, so the oil additive package likely saved it from scuffing. New rings, lapped the valves and put it back together good as new. I now use the Redline in the tractor, as it likely would not have sludged up with it's very high heat tolerance and hopefully prevented scuffing the same as the Penn oil.



I would not be afraid of the Valvoline 15-40 diesel oil mentioned in another post as SJ is the last of the good additive package oils and was high temp to address turbo bearing heat coking in that era, assuming that it still has the same formulation. The dual rating for diesel just means more soot handling additive in most cases.

[BillsPaseo]

I just bought a quart of the OnaMax 15W-40 on Amazon for $12.44 - hard to complain about that price when you only need one quart and only have to change it once a year...

[rowiebowie]

Thanks for all the replies. Since I have another generator (chinese Inverter) that specifies 15W-40 also, I'll probably stock that weight even though I'm perfectly in the 30W temperatures specified by Onan.

I may even be stubborn and insist on going full synthetic. I even found a Royal Purple 5 qt. on ebay I'm looking at.https://www.ebay.com/itm/Royal-Purpl...l/164132196014

[booster]

Originally Posted by rowiebowie

Thanks for all the replies. Since I have another generator (chinese Inverter) that specifies 15W-40 also, I'll probably stock that weight even though I'm perfectly in the 30W temperatures specified by Onan.

I may even be stubborn and insist on going full synthetic. I even found a Royal Purple 5 qt. on ebay I'm looking at.https://www.ebay.com/itm/Royal-Purpl...l/164132196014

Just for reference, that is a new standard SP oil, which is backward compatible to SN/SM so it would be reduced zinc additive package for modern engines.

[booster]

I heard back from Redline today in regards to their new and kind of confusing website specs.


Bottom line is that the Performance line is as it always was, with full Zinc additive package and full detergent for street use and also still a Gp5/4 base stock. Only the Performance series rated for Euro would be different. The Professional series are normal high end Gp3/4 oil with low zinc per rating rules.


So, all said and done, if we still had an Onan it would get the Redline 10W40 performance oil as first choice, and the Brad Penn 15W40 blend oil as a second choice. For an air cooled old school design engine, I think the additive package with high zinc is actually more important than the oil base itself. That is why I would not use the Royal Purple, even though they do make good products.

[rowiebowie]

Originally Posted by booster

I heard back from Redline today in regards to their new and kind of confusing website specs.


Bottom line is that the Performance line is as it always was, with full Zinc additive package and full detergent for street use and also still a Gp5/4 base stock. Only the Performance series rated for Euro would be different. The Professional series are normal high end Gp3/4 oil with low zinc per rating rules.


So, all said and done, if we still had an Onan it would get the Redline 10W40 performance oil as first choice, and the Brad Penn 15W40 blend oil as a second choice. For an air cooled old school design engine, I think the additive package with high zinc is actually more important than the oil base itself. That is why I would not use the Royal Purple, even though they do make good products.

Ok, thanks for the research booster. That answers a big question had regarding the zinc additive. An air-cooled old school engine is not the same as modern cars passing exhaust through emissions system. I did not know if the zinc was being lowered because that is good, or because of emissions. If higher zinc provides better wear protection, then that is the way to go.

Again, thanks.

[peteco]

Originally Posted by booster

I heard back from Redline today in regards to their new and kind of confusing website specs.


Bottom line is that the Performance line is as it always was, with full Zinc additive package and full detergent for street use and also still a Gp5/4 base stock. Only the Performance series rated for Euro would be different. The Professional series are normal high end Gp3/4 oil with low zinc per rating rules.


So, all said and done, if we still had an Onan it would get the Redline 10W40 performance oil as first choice, and the Brad Penn 15W40 blend oil as a second choice. For an air cooled old school design engine, I think the additive package with high zinc is actually more important than the oil base itself. That is why I would not use the Royal Purple, even though they do make good products.

With a high quality (and expensive) oil like this, do we really need to stick with the yearly oil change? I would think that if the engine is run monthly to drive out any moisture, and is not run for large hours, why wouldn't the oil last just fine beyond a year?

[avanti]

Originally Posted by peteco

With a high quality (and expensive) oil like this, do we really need to stick with the yearly oil change? I would think that if the engine is run monthly to drive out any moisture, and is not run for large hours, why wouldn't the oil last just fine beyond a year?

Agree. I've never seen any convincing argument (either real data or a theoretical analysis) that has convinced me that changing oil just due to calendar time makes any sense whatsoever. I am not even worried about moisture. First of all, oil is not hygroscopic; secondly, very little moisture enters the engine while it is just sitting. The problem occurs when moist air is sucked into a cold engine by starting it without being followed by a full warm-up to operating temperature. This is very bad and argues against periodically starting an engine during storage periods. However, the latter point is complicated in the case of Onan by the issue of keeping the generator's commutator surfaces shiny. Nothing to do with the engine or its oil, however.

Of course, I also believe that the "start it once a month year around" advice is ridiculous, so take that into account when evaluating my opinion on this topic.

[@Michael]

Originally Posted by avanti

Agree. I've never seen any convincing argument (either real data or a theoretical analysis) that has convinced me that changing oil just due to calendar time makes any sense whatsoever.

Also agree. I don't change oil on any engine based only on calendar.

Originally Posted by avanti

Of course, I also believe that the "start it once a month year around" advice is ridiculous, so take that into account when evaluating my opinion on this topic.

It would never occur to me to start my lawn mower or snow blower every month year around. Even with ethanol and without Stabil they still start fine after months of disuse - or years, in the case of my snow blower.

But for some reason my @#$%^ Onan runs like crap if I don't start it periodically - once a month or so. It'll start hard and barely idle until it runs for a few minutes. No idea why.

[booster]

Originally Posted by avanti

Agree. I've never seen any convincing argument (either real data or a theoretical analysis) that has convinced me that changing oil just due to calendar time makes any sense whatsoever. I am not even worried about moisture. First of all, oil is not hygroscopic; secondly, very little moisture enters the engine while it is just sitting. The problem occurs when moist air is sucked into a cold engine by starting it without being followed by a full warm-up to operating temperature. This is very bad and argues against periodically starting an engine during storage periods. However, the latter point is complicated in the case of Onan by the issue of keeping the generator's commutator surfaces shiny. Nothing to do with the engine or its oil, however.

Of course, I also believe that the "start it once a month year around" advice is ridiculous, so take that into account when evaluating my opinion on this topic.

I agree with most of want you say, but with a disclaimer a bit on the moisture, as I think that is dependent on use patterns and storage conditions. All engines will get a bit of moisture from a cold start ring leakage if they don't get fully warmed up during the use after that start. They will also pick up some moisture from hot/cold breathing through the crankcase breather setup. Cars a much more likely to get moisture from cold starts because they will pull in warm moist air through the PCV system and it will condense on the colder internal metal parts. Most small engines don't have forced crankcase ventilation so you get it much less. If stored outside, in humid climates, or with really wind temp variation, the crankcase will breath with temp changes just like a gas tank does and also build up a bit of moisture.


Our snowblower has gone years without an oil change, lawn tractor about 3 so far as we hire most mowing now except a once a year 6 hour swamp edge clearing, but they are stored inside in a heated garages, so much less moisture issues. Just "time" really isn't a criteria that I would put into the formula for changing. When we had the Onan, it was rarely used and had maybe two oil changes, and one was after breakin,

[rowiebowie]

Originally Posted by @Michael

But for some reason my @#$%^ Onan runs like crap if I don't start it periodically - once a month or so. It'll start hard and barely idle until it runs for a few minutes. No idea why.

While I didn't have the same starting problem you have, I agree that the more I exercise the Onan the better it runs. Last two times I've run it, the previous stalling problem has disappeared and the "occassional stumble" is now gone too. That was pulling 12 amps while charging my 200Ah lithiums at their highest 75Ah rate. I need to run the rooftop AC which draws 11 amps on low to see if the stumble is gone there too.

Maybe it's just my imagination, but now that it is running smoother, it seems quieter as well. The other day I was driving with it running (no load) and couldn't tell without killing the van engine and listening closely. I acutually stopped and walked around to the back to make sure. Fortunately, ours has never been intrusively loud and no real vibration to speak of enters the coach even went sitting in the back directly above it.

[peteco]

Originally Posted by booster

I heard back from Redline today in regards to their new and kind of confusing website specs.


Bottom line is that the Performance line is as it always was, with full Zinc additive package and full detergent for street use and also still a Gp5/4 base stock. Only the Performance series rated for Euro would be different. The Professional series are normal high end Gp3/4 oil with low zinc per rating rules.


So, all said and done, if we still had an Onan it would get the Redline 10W40 performance oil as first choice, and the Brad Penn 15W40 blend oil as a second choice. For an air cooled old school design engine, I think the additive package with high zinc is actually more important than the oil base itself. That is why I would not use the Royal Purple, even though they do make good products.

What is a good source for Redline?

[booster]

Originally Posted by peteco

What is a good source for Redline?

I think the last batch I got was from Summit Racing, IIRC. I was surprised at their price. I got the Performance oil in 5W30 for the van. It was about 18 months ago and I got it in gallon jugs. Plus a single quart to go with a few I still had to even out the changes.



Pricing on Redline seems to be very fluid with who is giving the best price, and the stuff is pretty heavy so if you can get free shipping it is a big deal.


Best to just figure out what particular oil you want and search it by description and also by the PN that you can usually get off the website pretty easily.

[peteco]

Here's interesting new information from Onan. They are now suggesting 10w-30 instead of 30w for gasoline/LP generators. I have always run 30w in my gas Onan, but considering booster's suggested 10w-40 Redline.

I wonder why they show the same temperature range for 10w-40 as for 10w-30.

Also interesting statement at the end: "Cummins does not recommend the use of Synthetic oil in Onan RV generators as there are no long-term benefits for the additional cost."

https://www.cummins.com/generators/m...-rv/onamax-oil

[booster]

Originally Posted by peteco

Here's interesting new information from Onan. They are now suggesting 10w-30 instead of 30w for gasoline/LP generators. I have always run 30w in my gas Onan, but considering booster's suggested 10w-40 Redline.

I wonder why they show the same temperature range for 10w-40 as for 10w-30.

Also interesting statement at the end: "Cummins does not recommend the use of Synthetic oil in Onan RV generators as there are no long-term benefits for the additional cost."

https://www.cummins.com/generators/m...-rv/onamax-oil

You see that 10w-30 and 10w-40 thing quite a bit on temp charts. If you look at the viscosity specs at the high temp end where the 30 or 40 is rated, you also may find one brand's 30 is like another brand's 40 viscosity wise. Pretty wide spec windows, I think. Part of it may be historically based also as back a number of years, in the early days of the wider range oils, the wider range oils got a bad rap for losing viscosity faster than the narrower range oils so that after a number of miles a 10w-40 might be less viscous at high temps than a 10w-30 would be. It was explained as happening because the wider range requires more viscosity improver additives which dilute the base stock, but I have no idea if that is true or not. Even if it was true, I don't think it is now, as the oil tests you see all the time on BITOG don't show huge drops at higher miles with the wider range products, especially in top line synthetics. One of Redlines big claims is that their ester GP5 basestock in their oils has a higher native viscosity index than the GP3/4 blends or dino oils do so they can use less of the diluting viscosity improvers and still get good viscosity range. It is interesting that the NASCAR cup engine are said to be using 5w20 most of the time and some messing with 0w20 all in the interest of getting a couple more horsepower. They do operate in a fairly narrow oil temp range though, I think.


I think Onan was just very slow in coming off of the old school oil specs for air cooled engines. The straight weights used to be considered necessary for the engines, probably to get them to hold oil better. Rings and seals have all gotten better, which likely helps some, but I also think they have learned that cold starts on 30 weight is not a good thing in general, and the same has been learned about the also old non detergent spec for no filter engines. I would agree in principle to the idea of synthetics being unnecessary and expensive for the most part as they engines will likely live to rated life pretty easily on dino oil if nothing bad happens. IMO, as mentioned often, it is the additive package that means the most under harsh conditions as that is what saves the parts when the inevitable metal to metal contact happens. That is why I would not hesitate to use the Brad Penn blend oil. I don't know if Onan/Robin did anything special like roller cams or rockers to help with the low zinc oils drivetrain wear and failure risk. The 2.8 Onan do seem to have an awful lot of valvetrain issues, though. Where a good high temp rated synthetic will save you is if something bad happens and the engine gets too hot. It can mean the difference between a destroyed engine and minimal damage in some cases. I think I read that the Onan 10w30 is an SM rated oil, but I don't recall where I saw that. That would make it low zinc.

[rowiebowie]

Another thing to avoid is the going to a "High Mileage" higher weight oil and then back to a non-High Mileage as mentioned in this thread earlier. There is a chance the seals will swell because of ingredients in the high mileage oil (unnecessary and undesireable unless you have an oil leak). Then the seals wear in at that status, but can leak when going back to "regular" oil.

The problem is, a vast majority of off the shelf retail 10w-40 is going to be diesel or high mileage formula. That is why these specialty oils like Redline and Brad Penn may be the best alternative.

I'm considering this one now. https://www.ebay.com/itm/Brad-Penn-H...UAAOSw5Ztafe04

It is the recommended 15w-40, semi-synthetic (splits the difference), and high zinc & phosphorus. Just need to shop and find a 6-pack at a much better price. Found a good 12-pack price, but that is just more than I need.

[@Michael]

Originally Posted by peteco

Here's interesting new information from Onan. They are now suggesting 10w-30 instead of 30w for gasoline/LP generators. I have always run 30w in my gas Onan, but considering booster's suggested 10w-40 Redline.

I wonder why they show the same temperature range for 10w-40 as for 10w-30.

Also interesting statement at the end: "Cummins does not recommend the use of Synthetic oil in Onan RV generators as there are no long-term benefits for the additional cost."

https://www.cummins.com/generators/m...-rv/onamax-oil

That's a big change. No more 15W-40 requirement for gasoline generators. Use either 10w-30 or 10w-40. No need to stick with SJ anymore. SM/SL are OK.

So now I can use whatever oil I have on the shelf.

Maybe they were having trouble sourcing the odd-ball 15W-40 SJ oil?

[VocalVirgo]

The difference between %w#0 and 10W30 is the cold start viscosity... with 5W flowing better in colder weather. So I wonder why the chart above has a much lower ambient temperature rating for 5W than 10W? It's the 30 that matters and is indeed the same viscosity once at warmed-up/running temperature. And in a brand new Onan, starting by using synthetic should be perfectly fine. I'm going to use 5W30 fully synthetic at my first change (20 hours) and continue to do so for 1000's of hours.