G'day ModBB and Bon_Scott
I feel there is a lot emotive puffery in understanding oils.
When I worked for a major oil maker - if you know what I men - I
came to realize that marketing was a smoke screen to oil reality.
Same oils were re-branded to reflect 'market placement' and ... profit.
The best guide for oil grade use was:-
The mower manufacturer's specification at the time (NOT brand);
The oil maker's claimed specification at the time.
When multi-grade oils hit the market I feel it was natural that
AUS mower makers would specify them - given the vast
differences in climate across this broad nation.
I'm sure - given the collaboration between mower makers and
oil companies - that recommendations followed profit,
not differences in oil actually required to do the job.
GTX was a great oil - but no different to any other oil
claiming the same specification. As Modd BB suggested,
advertising hype and puffery just disguised the reality.
Glo Mod Gadge is best qualified to answer this, because of his
direct experience in this industry.
Interesting topic
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Jack