Pilot Dar (multi grade oil)
Hi There PD
I would be interested in (what your problem is with "multi grade" oil)
Preheating in the UK in nearly unheard of (and so is dilution with fuel)
As the resulting "Carb fires" are usually an insurance job i assume no one gets excited re the situation.
I did my own tests and "switched " to a 15-50 (well known make) that sounds like bell.
I noticed at least two advantages :-
Much better starts in cold weather and pressure comes up quickly.
Much better exhaust valve lubrication during normal use.
If it is really cold (as we have experienced of late) i blank of the air intakes and give it half an hour with a fan heater.
The difference is amazing, it starts on the button (if it had a button) the pressure comes up and it runs smooth at once without having to do more priming or Throttle pumps.
AS for using multi grade in "hot" weather i have to say that my T&P's are always L&H in that order and one can always "top up" with mono grade between changes.
As the Machine gets used for "Towing" the tests were for real.
I found that there was a difference between the 20w50 and the 15-50 so stuck with the latter.
THis is with a Lyc 4 potter (180hp) that needs hardly any top ups and keeps its comp's up.
I am not suggesting that this oil would be suitable for a large radial with reduction gears but would not dismiss trying it out.