On Sun, 26 Jul 2020 13:48:44 +0100, Another John wrote:

Cheapest was a synthetic oil. I asked the lad there (an about-40 yrs
old lad, spent all his working life in the motor factors, and engines)
about mixing this with the oil I'd got: he said "doesn't matter - just
shove it in, as long as it's the right viscosity".

ISTR: there was once a time where the different additives in engine oils could
be incompatible, and cause it to gel or thicken. Along came the military, and
mandated that all oils be mixable without (drastic) downsides.

(I tried to find my source, but google groups seem more broken than usual,
returning 0 hits for "motor oil mix"...)


Thomas Prufer