Sulfated Ash/ Valve Deposits/ Air Cooled Engines?

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I have a couple of air cooled engines around the house. One of them is a Generac, standby 13kw, air cooled generator (natural gas fueled). Manual calls for using 5W30 API SJ. I was speaking with one of the oil company customer service reps about using HDEO (diesel engine oils) in this type of engine. In a nutshell, he discouraged it, "because of the higher levels of sulfated ash, in these hot running engines usually result in excess valve deposits."

In previous years, here in Michigan, I had run across the Canadian border and bought some Esso XD3-0W30 that I have been using year round in this generator. It has a listed sulfated ash % of 1.49 (which is pretty high). It was cheap and worked beautifully - so far.

Questions for the experts:

1) Should I discontinue the use of this oil in this application, or continue?

2) What is the concern of excess valve deposits in air cooled engines?

3) Has anyone using Delvac, Delo or any of the other HDEO's experienced a first hand valve deposit problem from long term usage? If so how easy/difficult are these deposits to remove?

If I discontinue using the Esso XD-3 0W30, I have some Mobil 1 0W30 to substitute year round. The only drawback to the "thin" (cst@100C is 10.3), Mobil 1 that I have noticed, is it tends to get "consumed" quickly in this type of engine. In a 3 day power outage, the generator would shut down due to low oil level before the 3rd day (oil capacity 1.7 qt with filter). The Esso XD3-0W30 does not burn off nearly so quickly (cst@100C is 12.1). I have noticed that the current CJ-4 Esso XD3-0W30 now lists a sulfated ash% of 0.99.



Comments?
 
I would use a natural gas engine oil such as Mobil Pegasus, I believe there is a 10W-30 available, as well as a synthetic 15W-40 Pegasus 1.

Pegasus 1 is such an awesome product name.
 
Originally Posted By: MGregoir
I would use a natural gas engine oil such as Mobil Pegasus, I believe there is a 10W-30 available, as well as a synthetic 15W-40 Pegasus 1.

Pegasus 1 is such an awesome product name.


I thought about that. Problem is:

1) No API rating listed for Pegasus. I have used the discontined Mobil 1Racing 0W30 in this generator before (which has no API rating either - but it is thin and also gets "consumed"). However it is meant for gasoline engines, which I think is the intent of mentioning the API designation in the manual.

2) Didn't know there was a 10W30 Pegasus. However, I sure would not want to be caught with the 15W40 Pegasus in winter, in Michigan. (We have had a few 3 day power outages in below 0 F weather, ice storms etc.)

3) I have never seen Pegasus sold anywhere, Where do you buy it? Anyone using it?
 
How many hours each year are you running this unit?? If it was your primary power generation source then I'd be worried...otherwise I'd run some Amsoil PI in the tank and run Rotella T 5W40 CJ4 in it and not worry.
 
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Mobil 0W40 would work too (breaks to a 30 grade pretty quick). Also you could run a synthetic 10W30 or 5W30 (Amsoil HDD) known for low consumption/Volatility and you wouldn't have to worry about it getting to the valves in the first place.
 
If you can go into Canada, what you need is 10W-30 Essolube G. It's a low ash NGEO for ligther duty engines, I don't think the oil is particularly special but it is meant for the application.

Really, any decent PCMO or 10W-30 CJ-4 oil will probably work.
 
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