Onan BFA Oil - Why not 20W-50?
Note: Our typical camping climate range runs from 10F to 115F (if we go to Redding, CA in the summer... otherwise up to about 105 in Southern Oregon.) Clearly Onan/Cummins have updated their recom...
Forum Discussion
RLS7201 wrote:udidwht wrote:RLS7201 wrote:KendallP wrote:
With all the viscosity index improvers needed to meet that wide spread in a conventional oil, you're not at all concerned about viscosity breakdown?
That is exactly why Onan didn't want multi-viscosity oil in their engines. Air cooled engines run hot enough to breakdown the VIs.
10W30 Non-Synthetic oil requires aprox. 11 percent VI. 10W40 requires 17+ percent VI. VI is not abrasive no is it a lubricant.
Many years ago, GM would cancel the warranty if they found 10W40 in the engine.
Some 10W30 synthetics do not require VI. So it should not be a problem in air cooled engines. Most 10W40 synthetics do require a small amount of VI.
I am privileged to have a petroleum engineer as a friend. The above info. comes from his desk.
Richard
An old wives tale from decades old ago that never went entirely away. VW used to also recommend straight weight oils. But that changed many years ago as multi viscosity oil improved.
Can you document your statement? Or are you just repeating rhetoric?
Richard
That is fact. Not really up for debate. This isn't the 70's
