I've got the larger T4 cooler in my T1 engine (theres a how to somewhere in this section) and i've seen oil temperatures drop 20 degrees or so on the gauge.
Re these any good http://www.ebay.co.uk/itm/Scat-VW-Full-Flow-Oil-Pump-w-Ext-Filter-1970-T1-Beetle-T2-Camper-Bus-Panel-Van-/160671410087?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item2568c327a7#ht_2242wt_955
You'll need to remove your engine mounting bar as it'll get in the way of the filter plus they also put the filter in the direct flow of heated air that has flowed over the cylinder heads. Stick your hand under the back of the van while its running and you'll feel the hot air. Better bet (if your case isn't already tapped for full flow oiling) would be to use one of these pumps: http://www.btowstore.com/epages/Store3_Shop2367.sf/en_GB/?ObjectPath=/Shops/Store3.Shop2367/Products/AC1151798 and mount a filter under the N/S battery tray or similar. An external cooler can then be added if you feel the need. Just a small modification is needed to the engine mounting bar for the hoses to clear.
I just removed one of the 3 mounts on the mounting bar that screw into the engine case (mines a bodged together 'previous owner special' of an engine bar with and early middle and T4 ends welded on though). The later style bar can be modded by cutting off and reversing one of the 3 mounts and welding it back on to clear the hose. I'll see if i can dig out a piccy.
I've done a single outlet/early mount bar one. I just moved the mounts back a bit on the chassis and packed out the mount/block a bit.
Make sure you have a temperature gauge. Then drive to that if the temperature gets high. Its interesting that "straight up" on the VDO temperature gauge is about 120 degrees C which seems to be the maximum typical running temperature for an aircooled VW engine. The bus has a 1641 cc TP engine with a single 34PICT-3 carburettor - with a twin quiet pack exhaust. If driven around 55 to 65mph it sits around 100 degrees C, so the 19 miles to work in heavy traffic the temperature never gets above 100 degrees. But on the way home the road is emptier... Driving at 70mph (GPS) or about 75 indicated on the speedo on the flat will bring it up to 125 degrees C. Thats fighting the added drag of a roof rack, Devon roof and an external sun visor. Then simply back off if it creeps higher . A couple of minutes at 60 mph and it cools down again. On long journeys we drive at 120 degrees C.
That would be a cool idea. The VDO oil temp gauge in my bus reads about 10 degrees out. At 100c on the gauge its really at 90c.
