what weight MOTOR oil do you use in your GAS motor home and GENERATOR

For those of you who have GAS what engine is it? Ford V8, V10, Chevy 6.0. 8.1?

And what weight motor oil do you use?
Conventional or synthetic?

What oil you use in your generator?

Does your engine consume much oil?

Shell rotella 15w-40 diesel oil in both. I think it's up to T4 now. Old MH is 460 Ford with about 75000 mi. on it. Put 2000-3000 mi. Year avg. change oil every spring, uses no oil, no leaks. Generator Onan Emerald 7k about 1200 hours. Put about 50 hours a year on it. Change oil every spring, uses no oil, no leaks. Had trucking company and bought oil in bulk (500 gal). Ran oil in everything,trucks, pickups, cars, lawn mowers, ect. Even put it on my bicycle chain. Never any problems. Some pickups had over 300,000 mi. on them when we sold them and were still running good. Of course many of the trucks had a million miles plus before overhaul or sell. Retired in May and sold company. Now buying oil at Walmart in 2.5 gallon containers.

I run Mobil 1 Extended Mileage 5-20 in our Ford Triton V-10, and regular Mobil 1 10-40 in the Onan 5500 generator. Both are full synthetics. Neither engine consumes any measurable oil between changes.

I am using conventional Pennzoil SAE 10-30 in my Chevy Workhorse 8.1L engine since it never gets that hot where I am taking it most of the time. I replaced the oil and filter at 7000 miles soon after I bought it, not knowing when it was last changed. I am about to change my Onan 5500 oil  (Onan 10-30 oil) and filter at 140 hrs of operation and simply vacuumed  the air filter.

Joel

For the generator I base my decision on the time of year and expected temperature range, for example when I changed the oil last week in preparation of our upcoming trip to Yellowstone, I picked SAE 30 which is rated for operation above 30 degrees F, I had considered 15W40 which is rated for 10F-100F, but thought SAE 30 would be safer given the summer heat we will likely see on the drive from Louisiana to Wyoming in August.

I am one of those crazies that runs what the manufacturer recommends in terms of weight.  Full synthetic though in ford v10.  The cost of full synthetic is much closer to conventional than it used to be but I read where the government loosened the requirements on what is considered "synthetic". 

Whatever the gen recommends - I forget hardly ever need to run it.

I also am leaving in the morning for a trip to Yellowstone, and on to Seattle. I just had the oil changed in my V10, at the Ford dealer, They used 5W-30 synthetic. I changed the oil in my generator and used Delo 15W-40 in it. I am slightly a contrarian to most folks on oil weight issues. I always try to use the lowest viscosity oil I can. Let me explain; Many of us know that most engine wear happens in that first 5 to 10 minutes after a cold start, when the oil is not yet fully up to temp and pumping well. Yet we almost always pick our oil viscosity based on that 1 hot day driving across the desert at 105 F. The truth is that even at 105F,  0W oil is too thick to properly lube an engine at startup. It is however much closer to a good flowing temp, and gets there quicker, than 10W-30, 15W-40, or straight 30 weight. Once up to temp 0W-30 performs exactly as 10W-30 or straight 30 for that matter, but it is flowing and pumping sooner. I use 0W-20 and 0W-30 in all my cars and small gas engines.

Use whatever weight of oil the engine or genset manufacturer recommends for the climate. Why would you presume to choose anything else? It's in the owner manual.

As for synthetic vs conventional, there is no question [technically] that synthetics have some superior qualities. If the cost were the same, choosing synthetic would be a no-brainer. Whether that translates into any practical benefit for the vehicle owner is a more difficult call. Use of a conventional oil that meets the engine builders requirement for API Service Class is entire adequate to provide a long and healthy life in normal operating conditions. Some people choose synthetics as a way to extend the oil change interval, while others may simply feel they are being kind to their expensive engine by giving it the best possible care regardless of cost.

Bob Is The Oil Guy has the most informed information about oil.
https://bobistheoilguy.com/

Gary RV_Wizard said:

Use whatever weight of oil the engine or genset manufacturer recommends for the climate. Why would you presume to choose anything else? It's in the owner manual.

As for synthetic vs conventional, there is no question [technically] that synthetics have some superior qualities. If the cost were the same, choosing synthetic would be a no-brainer. Whether that translates into any practical benefit for the vehicle owner is a more difficult call. Use of a conventional oil that meets the engine builders requirement for API Service Class is entire adequate to provide a long and healthy life in normal operating conditions. Some people choose synthetics as a way to extend the oil change interval, while others may simply feel they are being kind to their expensive engine by giving it the best possible care regardless of cost.

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I agree with the Wizard ditto...

I use the viscosity the mfg calls for. 

As for brand, I use Walmart.  That is pretty much based on a consumers report from some 20-30 years ago where they took about 60 (or maybe it was 120) taxi cabs in NYC.  They broke the engines down and measured the dimensions of all the wear points in the engine.  Put everything back together and ran half on more expensive and supposed to be "better" oil. The other half they just ran house brand oils.  Note, all oils were rated at the latest alpha code spec on the bottle available at the time.  At about 60,000 miles they broke the engines down again and remeasured.  No differences in the wear with house brand and expensive oils. 

I believe they also changed the oil on some every 3,000 miles and on others every 6000 miles.  No difference in wear. 

I suppose, and perhaps could agree, that if you were to run an engine in your vehicle for 300,000 or 500,000 miles then you might see a difference. 

However by the time my vehicles are at the 150,000-200,000 mile mark the least of my issues are with the engine and if the wear points are beginning to show wear. 

Air conditioner, heater core needing to be replaced, power steering pump, power windows and lots of other little things begin to go kaput. 

No mention of transmission has been made. 

Pulling the load of an RV you put a stress on the transmission.  You really should replace the fluid every 30,000-50,000 miles.  Most people ignore this little item, but are right on about changing the engine oil. 

The Ford 5 speed requires a specific transmission fluid, that I can only find at a few specialized stores and Ford dealerships.  NAPA, Auto Zone,etc don't carry it.  It runs about $7-$8/quart. 

AStravelers said:

...As for brand, I use Walmart.  That is pretty much based on a consumers report from some 20-30 years ago where they took about 60 (or maybe it was 120) taxi cabs in NYC.  They broke the engines down and measured the dimensions of all the wear points in the engine.  Put everything back together and ran half on more expensive and supposed to be "better" oil. The other half they just ran house brand oils.  Note, all oils were rated at the latest alpha code spec on the bottle available at the time.  At about 60,000 miles they broke the engines down again and remeasured.  No differences in the wear with house brand and expensive oils... 

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i have to wonder if this would be true for standard vs. synthethic oils.  My guess is that synthethics would have had a better life.  While I use synthetic oil in my cars I have a small engine oil leak in my RV that would make this a waste as I am regularly adding oil.  I replaced the seal at where the odometer pickup is located, but there is another leak that looks more difficult to repair. Adding a little oil is more cost effective.

I go by what the owner's manual says - 10W-30 for the engine and 30W for the generator. To simplify things, I carry 10W-30 for both while on the road. The generator oil gets changed every 150 hours as the manual recommends and the engine oil is changed between 3,000 and 6,000 miles, depending on the kind of driving I have just done. Easy interstates with no mountains and I'll go the max; mountainous roads, or a lot of stop and start driving and I'll go the minimum.

I just changed to oil in my genny, (4000 watt Onan). I used 10w40 Shell. The motorhome will probably just go to my local Ford dealer, as they can handle a class C, and I can get a decent price for an oil change there.

I'm with jubileee, Rotella 15/40 in both my motor homes,(don't ask  )  all my cars (3), motorcycle, lawn mower, wood splitter, portable generator, motor home generator, and even my old Ford farm tractor. After 35+ years working on heavy equipment, I found no better all purpose oil.
After some thought, I do admit I used synthetic oil in our race cars.

Gary RV_Wizard said:

Use whatever weight of oil the engine or genset manufacturer recommends for the climate. Why would you presume to choose anything else? It's in the owner manual.

As for synthetic vs conventional, there is no question [technically] that synthetics have some superior qualities. If the cost were the same, choosing synthetic would be a no-brainer. Whether that translates into any practical benefit for the vehicle owner is a more difficult call. Use of a conventional oil that meets the engine builders requirement for API Service Class is entire adequate to provide a long and healthy life in normal operating conditions. Some people choose synthetics as a way to extend the oil change interval, while others may simply feel they are being kind to their expensive engine by giving it the best possible care regardless of cost.

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Hi. As usual.....great info. My onan is a 2002 model. Runs super. I just got the coach and want to change the gen oil. The original onan manual calls for SG, SH, or SJ spec. Those all appear to be out of date. What API specs do I use for a guide? Thanks. Howard, Texas

howardtx said:

What API specs do I use

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That was a five year old post you replied to.

I have never done such. If you believe that, I have another one to tell you.

The letter after the "S" is what you go by. The higher letter the better. Old oil will be SA. newer oil will be "SP" these days. But if you see a SQ or SR, it will be even better.

When a better additive is discovered, they put it in all the conventional engine oils and raise that letter to the next higher.

-Don- Auburn, CA

Thanks so much for the input. Howard

Howard, the Onan generators we had (a 1987 & a 1998) both used 30 weight oils. I just used the SAE30 in the 87 and 15W-40 oil in the 98 as I also used them in the chassis engine.