What type of rear in oil should I use?

[Pinger]

I have a good quality oil lined up for this.

Re synthetics versus minerals.
Synthetics have some advantages mainly in at the extremes of the temperature range. The absence of napthenics and aromatics (which are present in most mineral oils with the exception of pure paraffinic bases) can give them an edge in high temp applications. They also tend to control molecule size better.

But, what they lack is solubility. Solubility (natural in mineral oils) allows for the uptake and retention of all the different additive packages (eg, anti-wear, anti-foam, tackifier, detergent, anti-oxidants, etc) thus a synthetic is compromised as to how robustly it can dosed with additives. Often enough, oils are changed out not because the oil is bad but because the additive packages are depleted. If they were limited at the beginning then obviously they will deplete earlier. This issue of solubility is why engine oils tend not to be pure synthetics but semi-synthetic where they are blended with mineral oils for their solubility.
(This is my line of work BTW).