2005 Generac GTV-760 Oil Pressure Problem

[bijiminy]

I have been running Castrol 10w30 in this engine on the advice of the local Dixie Chopper Dealer, even though Dixie Chopper recommends Lucas 15w40 specifically for this engine. He had previously serviced this engine with 10w30. I was amazed this dealer had never heard of a Generac engine in a Dixie Chopper. He assured me 10w30 would not hurt the engine. Recently the temperature outside has reached near 100 degrees and the oil pressure warning light started going on and off. I'm hearing no clattering, the engine does not shut down though I don't think this mower has this feature. The engine is not low on oil and the oil is still clean. The engine has just turned 600 hours. I added just a little more oil since I was running 2.0 quarts, to just get it to the full mark, instead of 2.4. It is now above the full mark. It didn't make any difference. Light is still flashing. The engine runs very well. I'm not hearing any strange noises, starts on first turn, which make me think I possibly have a oil pressure switch problem and maybe I should be running the recommended 15w40. I ordered a gallon of the Lucas 15w40 oil and a new switch. Should I worry that I have harmed my engine from bad advice or what? Is my thinking correct on this? Thanks for any advice..

 

[slomo]

Look at your engine manual for proper oil recommendation.

I wouldn't run multi weight oil in an air cooled engine.

A 10 grade oil as in 10w-30 is just that, 10 grade. SAE30 oil is a 30 grade oil, much thicker. Peak summer temps like now..... See where this is going? Even a 15w-40 is a 15 grade that acts like a 40 when at 212F. Briggs and Stratton says if you run multi, it will use more oil and to check more often.

 

[bijiminy]

Look at your engine manual for proper oil recommendation.

I wouldn't run multi weight oil in an air cooled engine.

A 10 grade oil as in 10w-30 is just that, 10 grade. SAE30 oil is a 30 grade oil, much thicker. Peak summer temps like now..... See where this is going? Even a 15w-40 is a 15 grade that acts like a 40 when at 212F. Briggs and Stratton says if you run multi, it will use more oil and to check more often.

Thanks for the reply. The manual says Lucas 15w40. It's Diesel oil. Don't know why Dixie Chopper recommended this oil in 2005, but that's what the manual says. The engine is running fine. Just this idiot light kept flashing at near 100 degree weather. I don't hear any strange noises. I ran it at the end of all last summer and most of this summer with 10w30, because I bought it that way, but the temps were cooler up until last week. The local dealer had already serviced it with 10w30. He never heard of Generac engines being used in Dixie Choppers. I called him and that was what he told me. So you think I should run straight 30 weight? Or use the recommended oil? I'm going to change the oil and the oil pressure switch. I used to use straight 30 weight in my old air cooled Volkswagen, but people have told me the newer oils are better. I don't think I hurt the engine, but I really think this switch may be bad. I'm an old timer, and I believe what you said. Use straight weight in an air cooled engine. Probably straight 30w. Thanks again. I really appreciate your response. It makes sense to me.

 

[StarTech]

Personally I started putting 15W50 Kawasaki synthetic oil in all the oil pump engines because the extreme Summer air temps. But Mobile One makes 15w40 Synthetic oil too.

And yes the oil pressure switch or wiring may be the problem. Only an oil pressure gauge will tell if the oil pressure is fluxing.

 

[Scrubcadet10]

Diesel (Rotella) oil is "best" for Air Cooled engines... modern auto oils don't have certain anti wear additives they used to... i use Rotella SAE 30 in my push mower (heck, for $4.50 a quart) and 15W40 Rotella in my Kawasaki engine,
I use Kawasaki K-Tech as my shop oil for changes for other peoples mowers as it is designed for air cooled engines.

 

[slomo]

Diesel (Rotella) oil is "best" for Air Cooled engines... modern auto oils don't have certain anti wear additives they used to... i use Rotella SAE 30 in my push mower (heck, for $4.50 a quart) and 15W40 Rotella in my Kawasaki engine,
I use Kawasaki K-Tech as my shop oil for changes for other peoples mowers as it is designed for air cooled engines.
View attachment 57728

Noticed a while back. These viscosity charts are strange. Some charts say for example SAE30 is only good for 35C or 95F. Just like the Kawasaki chart you posted. Others say SAE30 is good to 104F ambient. Only a handful of degrees I guess. Here's a couple examples. Don't know what it proves?? Guess follow your engine manual on oil specs.

 

[slomo]

As you see the above charts are from different sources. Two mower related are from Briggs and Snapper. They don't even agree. Again only a couple degrees. Guess I will keep using SAE30, never lost an engine yet on it.

 

[bertsmobile1]

the oil has to float the bearing
What decides if it can do this is, the size of the oil hole feeding the bearing, the pressure that the oil is under , the space between the journal & the bush , the viscosity of the oil.
The first 3 are manufacturing fundamental of the particular engine

 

[bijiminy]

the oil has to float the bearing
What decides if it can do this is, the size of the oil hole feeding the bearing, the pressure that the oil is under , the space between the journal & the bush , the viscosity of the oil.
The first 3 are manufacturing fundamental of the particular engine

Now I'm confused. I was going to go with 30w, but now maybe I should go with factory recommendation. I'm pretty sure I have a bad oil pressure switch. Cleaned the contacts. Idiot light still flashing. I think if I had real problems with the engine, it would have stopped by now. Keeps on purring. I have real respect for these old Generacs as long as they are taken care of. I don't want to use synthetic after using conventional. Had a bad experience in the past.

 

[StarTech]

Yes these pressure switches do go bad. Even the local dealer just told the customer to ignore the light as the engine had no oil pump when the switch was bad. What an idiot. If he only had looked at the engine or the IPL he would have know differently. I replaced the pressure and switch the light stayed out. But of I course checked the oil pressure to make sure there wasn't a problem.

Now the customer will not even let the JD dealer even touch either his Z925A or his Z950M. The Z950M was new and under JD warranty when he started having me to service it. And I had to do a triple bypass of the computer on the 925 as it failed partially.