If you're losing a lot of oil then there should be good evidence on the engine. I'm sure you know most of the usual places, so consider this checklist a reminder.

Excessive crankcase pressure is often behind oil leaks at weak points like oil seals (or worse still pushing them out, often the case when there is significant oil loss), so always start there.

a) Check and clean your PCV system, flame trap element, small hose to throttle body (incl nipples both ends and the tiny holes in the throttle body throat, also a good excuse to remove and thoroughly clean the TB ).
b) Check for a plugged oil separator (remove the oil filler cap and try blowing back into it through suitable vinyl tubing). A badly dried out O-ring at the base is a less common source of leaks, but if you've had the oil box out and didn't replace the O-ring or properly tighten it then a distinct possibility.
c) Check around the valve cover, especially the front edge.
d) Check for leaking front oil seals, either worn or pushed out from crankcase pressure. Check for evidence of oil at the bottom of the lower timing cover. It's often grungy there anyway, so if it's not fresh oil then wipe clean and recheck after some driving. If you need an excuse to replace the timing belt then this is it so you can remove the timing belt covers for a full inspection and seal replacement. If the seals haven't been done in living memory then replace them all.
e) Check the back of the block for oil leaking out under the distributor. If suspected there then check inside the distributor cap. Worn O-rings and the distributor shaft bushing can leak oil down the back that can make you think it's the rear main seal.
f) Check under the oil filter in case it's not properly sealed or a wire accidentally got pinched behind the seal at the last filter change.
g) Saving this for last in bad weather, you need to crawl underneath and see if it's the oil pan, drain plug and yes, the rear main seal with excessive oil coming out from the bell housing. If you don't see fresh oil then clean off all the grunge and see if it comes back. If it is the main seal and because it's such a hassle to replace then as long as it's not pushed out, cleaning the PCV system can often slow the leak to a tolerable level (often my case).
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now