Need help picking correct oil for my 25 year old 19hp twin Generac generator

[sixdogs]

What is the correct oil to use in my 25 year old 19hp, twin cyl, air cooled Generac generator. This is from the old days with higher ZDDP in the oil and I don't want to screw up my house generator with modern oil. The generator has test run more than actual use and only has maybe 15 hours of non-test use. So the rings aren't even seated yet.

Here's my engine, front ID tab and owner's manual oil requirement

What I have been using is some ag gas engine oil that correct for the but is 30W and I want to go lighter like 10W30 or even synthetic for the winter. I could also use modern oil and just add a little ZDDP additive. I have done this with other gas engines and know the % mixture from company instructions

But, here's what I saw the other day in a shop but I know nothing of these oils. Does anyone know anything about these?


My plan at the moment is confusing. Should I just use modern synthetic gas engine oil if OK for rings seating, add a little ZDDP and call it good or go with a pre packaged oil as shown in the pictures? Are they really different? Any knowledge or help appreciated.

 

[RustyA]

If the zinc content is a concern for you I would consider a diesel rated oil like rotella t6 full syn 5w40. Zinc content is greater than newer G rated gas oils that are formulated for longer catalytic converter life. I use it in all my non emission engines, ATV, zero turn, splitter, and boats.

 

[grsthegreat]

I maintain generac standbys for a living……i only use mobil 1 5W30 here ….. its what generac recommends. Even for generators back to 2004 ish. Those are the oldest ones i maintain. I dont use any additives, and generac does not recommend ever using an additive.

just my opinion.


but im in north idaho. For warmer climates the older 2004 era units had a chart for oils. This was back when synthetics were just gaining ground. Nowdays they just recommend a full synthetic 5W30 after breaking in engine.. heres a screenshot of older manual

 

[sixdogs]

I maintain generac standbys for a living……i only use mobil 1 5W30 here ….. its what generac recommends. Even for generators back to 2004 ish. Those are the oldest ones i maintain. I dont use any additives, and generac does not recommend ever using an additive.

just my opinion.


but im in north idaho. For warmer climates the older 2004 era units had a chart for oils. This was back when synthetics were just gaining ground. Nowdays they just recommend a full synthetic 5W30 after breaking in engine.. heres a screenshot of older manual


View attachment 857295

Thank you. I bought this generator in 1999 so it's old school. Do you know if I can use synthetic from an engine built back then? Do they sell a specific break-in oil? I have JD diesel break-in oil and I know that has higher ZDDP. How long is the break-in period?

 

[RandyT]

All of the modern small engine oils contain ZDDP So Briggs, Kohler, Honda, Stens, Kawasaki, Kinetix, other brands small engine oils will have the required additives for your air cooled engine

 

[RandyT]

Been working on, rebuilding, and replacing small engines on lawnmowers etc for over 26 years, and I have never come across an OEM that recommends the use of breakin oil in any of their engines even when new out of the box.

 

[grsthegreat]

generac does not use a break in oil in new engines. they come with dinosaur 5-30 oil from factory, and they recommend swapping to synthetic after 25 run hours. but, if you add winter heat option (wrap oil filter heater) they recommend swapping to synthetic immediately. they dont want ANY additives used.

 

[5030]

Been working on, rebuilding, and replacing small engines on lawnmowers etc for over 26 years, and I have never come across an OEM that recommends the use of breakin oil in any of their engines even when new out of the box.

Actually, Generac does and they recommend running the initial factory fill for (I believe) 20 hours. Cannot remember and mine is pretty old as well, mine is a 19KW for the house standby and ever since I've been using Rotella T5 in it plus a filter change and air cleaner renew every spring. Interestingly, my steel cabinet is about rusted out and Generac sold me an aluminum enclosure of the same square design as my old cabinet is. Wasn't cheap but cheaper than buying a new complete unit. I also have a JD diesel powered 30 KW standby to run the shop and all my 3 phase equipment.

 

[sixdogs]

Actually, Generac does and they recommend running the initial factory fill for (I believe) 20 hours. Cannot remember and mine is pretty old as well, mine is a 19KW for the house standby and ever since I've been using Rotella T5 in it plus a filter change and air cleaner renew every spring. Interestingly, my steel cabinet is about rusted out and Generac sold me an aluminum enclosure of the same square design as my old cabinet is. Wasn't cheap but cheaper than buying a new complete unit. I also have a JD diesel powered 30 KW standby to run the shop and all my 3 phase equipment.

What weight Rotella T5 are you using? I might have the same 19hp engine.

 

[90cummins]

Zddp isn’t a requirement for Generac air cooled engines or any othe fact.
Zddp was essential for cam lifter protection in cars especially those with higher performance engines with wilder high lift camshaft’s & heavy valve springs.
Oils have been reformulated to with other additives to replace the zddp.
I would use a quality 10-30 for mild climates & a 5-30 synthetic for colder climates.
Small diesels depending on design such as an air cooled L series Yanmar require a diesel oil to protect the cam/injection pump lifter from scuffing from my experience.
I’ve never seen a worn cam/ lifter on air cooled small engines.
I just rebuilt a Generac 25kw 990cc v-twin & the cam was spotless.
It came in because of excessive blow by because a foreign object went thru it. New pistons & rings with a quick hone & it’s ready for service.
Go to bobistheoilguy forum for everything you want to know about oil for any application.
Great website!!
90cummins

 

[RandyT]

Actually, Generac does and they recommend running the initial factory fill for (I believe) 20 hours. Cannot remember and mine is pretty old as well, mine is a 19KW for the house standby and ever since I've been using Rotella T5 in it plus a filter change and air cleaner renew every spring. Interestingly, my steel cabinet is about rusted out and Generac sold me an aluminum enclosure of the same square design as my old cabinet is. Wasn't cheap but cheaper than buying a new complete unit. I also have a JD diesel powered 30 KW standby to run the shop and all my 3 phase equipment.

Went and looked at a couple service manuals. And it says that the generator is run and tested at the factory, and no breakin required. And to change the oil after the first 25 hours for breakin. That doesn't mean they used breakin oil at the factory or recommend the use of breakin oil in their engines.

 

[5030]

Been a long time (at least 15 years since I got mine so I'm sure you are correct), without getting my owners manuals out, which I have btw. Like I said, my current issue is the enclosure is rusting way but I have a full aluminum enclosure that the unit will go in once the weather warms up. it wasn't a cheap date but I have it none the less and that tells me, they are making upgraded enclosures for the older (steel cabbed) units.

It was 4500 bucks delivered by commercial carrier but a heck of a lot cheaper than a new comparable unit.

My diesel powered (JD) unit is also in a steel cabinet but I've had no corrosion issues with that one at all, interestingly.

Never had issue one with my Generac standby except I had to replace the starter which wasn't a big deal and I read they had starter issues, I did. Both the diesel unit and the propane fired units have really been 100% without issues the whole time I've owned them other than routine maintenance which is required anyway. My 3 phase unit is plumbed directly into my 500 gallon diesel bulk tank btw. Very good units and I recommend Generac, besides they are easy to deal with.

 

[5030]

I have enough electrical knowledge that I installed both myself other than the propane fired unit which I had my local propane supply plumb for me.

I believe the 'trick' to longevity is timely maintenance. . Like I said, I run Rotella T4 in both of them, always have.

 

[grsthegreat]

Actually, Generac does and they recommend running the initial factory fill for (I believe) 20 hours. Cannot remember and mine is pretty old as well, mine is a 19KW for the house standby and ever since I've been using Rotella T5 in it plus a filter change and air cleaner renew every spring. Interestingly, my steel cabinet is about rusted out and Generac sold me an aluminum enclosure of the same square design as my old cabinet is. Wasn't cheap but cheaper than buying a new complete unit. I also have a JD diesel powered 30 KW standby to run the shop and all my 3 phase equipment.

Ive taken generac service classes. They DO NOT use a break in oil In their air cooled standby units. Only non synthetic 5W30 oil in their standbys. They specifically tell us to “DO NOT USE OILS WITH BREAK IN ADDITIVES”. The only thing they do use in original oil is a UV dye. This is used to check for leaks during testing.

i have no idea what they use in the liquid cooled units as i dont service those.

 

[RandyT]

Ive taken generac service classes. They DO NOT use a break in oil In their air cooled standby units. Only non synthetic 5W30 oil in their standbys. They specifically tell us to “DO NOT USE OILS WITH BREAK IN ADDITIVES”. The only thing they do use in original oil is a UV dye. This is used to check for leaks during testing.

i have no idea what they use in the liquid cooled units as i dont service those.

I just service and warranty the portable products and for the most part don't service the standby units, other than when my regular mower repair customers ask me to do the service.

 

[5030]

What the heck is 'break in oil' anyway. Never heard of it.

 

[sixdogs]

Went and looked at a couple service manuals. And it says that the generator is run and tested at the factory, and no breakin required. And to change the oil after the first 25 hours for breakin. That doesn't mean they used breakin oil at the factory or recommend the use of breakin oil in their engines.

I'm the OP and my engine was built in 1999. Did they build engines differently then with different break in comments?

 

[RandyT]

What the heck is 'break in oil' anyway. Never heard of it.

Breakin oil is an oil that doesn't have friction modifiers to assist in the seating of rings to the cylinder for better compression. Normally used more with race engines at this point, but use to be more common years ago.

 

[RandyT]

I'm the OP and my engine was built in 1999. Did they build engines differently then with different break in comments?

Wording over the years has changed. Current small engines recommend the first oil change after 5 hours on engines without oil filter. And 100 hours on engines with oil filter. Some other engine OEM's will have a recommendation of 20 or 25 or 50 hours for first oil change.

Throw synthetic oils into the mix and recommendation charts have changed drastically and can vary by oil used. for instant Briggs will say to use 5W30 in temps below 40 degrees but their own branded 5W30 can be used for temps upto 100 degrees.

There is also confusion when people talk about using breakin oil. Special cases require the use of the actual breakin oil. but what most people refer to breakin oil is actually the first normal oil added to a new engine or rebuild engine that is run from 2-5 hours and then changed.

 

[5030]

Ive taken generac service classes. They DO NOT use a break in oil In their air cooled standby units. Only non synthetic 5W30 oil in their standbys. They specifically tell us to “DO NOT USE OILS WITH BREAK IN ADDITIVES”. The only thing they do use in original oil is a UV dye. This is used to check for leaks during testing.

i have no idea what they use in the liquid cooled units as i dont service those.

My diesel standby has a John Deere engine anyway. I believe Generac uses not only JD engines but Cummins and Ford (gas) engines in their larger standby units.