I run 10/30 Mobile 1 in the Generac I have in the coach. As I do not run the generator that much I change it every other year just for grins. I run my generator for about 30 min every 4 to 6 weeks.

JR Wright
78 Buskirk Stretch
75 Avion

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I'm changing the oil in my lawn tractor and thought I'd do the GMC's Onan as well. Is anyone using synthetic oil in their Onan?

The reason I ask is that Briggs and Stratton recommends standard SAE30 for temperatures above 40 degrees, and 5W30 or 10W30 for under 40 degrees. They also recommend synthetic 5W30 to 10W30 for use from below zero to over 100 degrees. I like this option because I use the lawn tractor both to mow the lawn in the summer and clear snow in the winter. Briggs and Stratton mentions that the use of non-synthetic oils at temperatures above 40 degrees may result in higher oil consumption since the engine runs hotter.

Page 12 of the Onan manual shows SAE30 or 10W40 for temperatures above 30 degrees, 5W30 or 10W40 for zero to 30 degrees, and 5W30 for below zero. My understanding is that SAE30 is better for summer use due to lower oil consumption. But since we occasionally use the Onan during the winter in temperatures below 30 degrees, would a synthetic oil work better across a wider temperature range without the consumption problems of multi-viscosity standard oils? Any drawbacks?

If there's ever an application that deserves synthetic the Onan is it, but it sure does leak if your Onan is like others

I'm changing the oil in my lawn tractor and thought I'd do the GMC's Onan as well. Is anyone using synthetic oil in their Onan?

The reason I ask is that Briggs and Stratton recommends standard SAE30 for temperatures above 40 degrees, and 5W30 or 10W30 for under 40 degrees. They also recommend synthetic 5W30 to 10W30 for use from below zero to over 100 degrees. I like this option because I use the lawn tractor both to mow the lawn in the summer and clear snow in the winter. Briggs and Stratton mentions that the use of non-synthetic oils at temperatures above 40 degrees may result in higher oil consumption since the engine runs hotter.

Page 12 of the Onan manual shows SAE30 or 10W40 for temperatures above 30 degrees, 5W30 or 10W40 for zero to 30 degrees, and 5W30 for below zero. My understanding is that SAE30 is better for summer use due to lower oil consumption. But since we occasionally use the Onan during the winter in temperatures below 30 degrees, would a synthetic oil work better across a wider temperature range without the consumption problems of multi-viscosity standard oils? Any drawbacks?

Bob de Kruyff wrote on Sat, 12 July 2014 19:45

If there's ever an application that deserves synthetic the Onan is it, but it sure does leak if your Onan is like others

Bob that's an interesting comment. I would think such a big hunk of metal running at controlled speeds and known max load would have a well defined oil need. What are you aware of that causes you to feel that way (leak comment not included in this question).