We just installed a 20 KW standby gen system at our home. After 8 hrs. they require the break in oil be changed.They recommend 5/30 synthetic. The engine is a 36hp twin air cooled engine. My question is, on my previous smaller 16 hp 7.5 kw unit I have tried M1 5/30 and 20/50. The 5/30 needs to be added at a significantly more frequent rate than the 20/50. This new setup runs once a week, automatically, for 10 mins to test the system and lube the engine. Since we can have outages that last 5 days what oil coukd I use that will not run through the engine as fast as 5/30 but not be as viscous in the dead of winter as 20/50?