Only when cold, my oil pressure light came on this morning when I cornered (at speed though).

I know the oil level is good and this is the only time it has done this. Any suggestions on what it could be caused by?

Too thick oil, not returning to the sump quickly enough while cold

also recheck the oil level

Oil - not sure it has what was in it when I bought it.
Screen - same goes, no idea of condition.
Oil level is upper range of the dipstick as checked on a flat surface.

Vehicle is due for a service so maybe it is a good time to ask what is the best oil to put in it (although I want to do the seals before servicing it).

So best oil brand and grade - it is a twin port 1600 in a 73 Kombi.

Also is it recommended to flush or not to flush the engine?

Thanks for the advice.

Change the oil and clean the screen while you're at it. You'll need to buy an oil gasket kit which will include new copper compression washers for the sump plate (you don't want it to leak, do you?). You can get the gasket kit for a few bucks from any aircooled VW mechanic or spares supplier.

The best oil to use is Castrol GTX 20W-50 in the [size=5]white[/size] bottle.

Confusingly, they also make another product with the exact same name in a grey bottle. It won't hurt your engine, it just won't give quite as good protection against heat damage. So use the one in the white bottle.

This is the one you want:
http://www.castrol.com/castrol/productd  ... Id=6008619

I'm pretty sure the 20w50 white bottle is what I have - used to use it in my Landrover and bought some extra from Aldi when it was on special. I plan to do the seals, gaskets, clean and service and oil change in the near future plus all my ignition leads are looking tired (the rubber cups are cracked), just need to find a spare half day to get a few bits done. She needs a new muffler as well soon.

I use German Fuchs 30 grade n have also used 'Ace' air cooled
castrol only if.. nup never used it in an air cooled, I like my vw's too much

Are any of the oil stabilising additives recommended? Or just go with a good standard oil? I take it the screen on these is the only filter? I have a haynes manual but have not read through it yet.

Don't use an oil additive, just a good oil is required. Yes, screen is the only 'filter' fitted from standard, must be cleaned every service to combat sludge formation.

We've seen screens that have not been removed for Y e a r s . Also some that have been Very Permanently silasticed-in to prevent leaks! One engine of ours had significant amounts of fibrous insulation & other garbage partly blocking the screen (but had had regular receipted services, following rebuild, by a VW specialist* according to the previous owner). If there is a build-up of any great amount of 'crud' it may be a good idea to do two changes in short succession, cleaning the strainer & plate each time. Do not use anything above "25W - 50" in viscosity, that could be too thick for your 1600 (unless it is on it last legs? which it doesn't sound like). "Oil stabilisers" (an oxymoronic? name as they are thermally unstable) will thicken the oil, temporarily, & may make the light come on longer. [There may be a some use, in a temporary extension ofengine life if compression is low ?] If poss. also try to get oil rated SG (common), SH (extinct?), SJ (rare now), or SL (common recently). These tend to have good levels of additives. And/or a diesel rating of CF-4, CG-4, or CH-4 may also be desirable. These tend to have good levels of detergents. (Ignore "CF", it's not relevant.)
*since gone.

As someone who likes to do 5000km changes of oil and filter I'll be on that, I dislike the idea that some people have of using silastic as a solution for everything. Most of my oil drips that I've seen are from a combination of tappet cover gaskets and pushrod tube seals, both of which I plan to do very soon.

What about using sump flush solutions to wash out all the crud? Or is this a no-no?

Engine seems in good order, starts on first kick and doesn't smoke, knock or any other nasties. I'd like to keep it in such a state for as long as possible given that I don't do too many k's in a year (only around 400 a month) which is down from my last vehicle which did 450 to 500 a week.

I was hoping someone else could answer that. A few people seem to use those flushes routinely. We've only used them rarely, eg. on a newly acquired engine that has been neglected and is clearly very "clagged up" with varnish, gunk, etc. Seem very effective. I've sometimes wondered if the deposits/varnish is helping hold some vital part in position! They have, I believe very high levels of the same sort of 'oil detergents' that are in oils anyway, maybe some solvent too; not sure. I'd have a look at your engine before trying it, ie. check under rocker covers, inside breather, and via the strainer plate... If it all looks clean, there's probably no need. If used, don't leave it in too long before draining the oil (while hot). May be worth doing a second oil change fairly soon, if there is a lot of gunge the first time, esp if you flush.

How beneficial are those extended sumps and other such add ons? The ones that bolt on where the screen plate fits and offer increased oil capacity and a removable filter? Do they do anything to help or are they just a gimmick?

Brutus - the point you made re the gunk dislodged by the flush is what worries me. I haven't seen any concrete evidence either way to say what is good or bad.

I have seen quite a number of engines suffer from a flush.
Hydraulic lifters which were fine before became extremely noisy and had to be replaced.
Also engines which were otherwise okay became smoky when carbon was stripped from the rings.
For mine, stick to a good oil and do a few early oil changes.