Which oil do I need??

I've got a 1991 MK1 1.8 GTI Cabriolet that I purchased on Saturday…………which engine oil do I need?

10W 40 semi Semi-Synthetic oil.
I used to use this stuff before my car started burning oil, (256,000 miles, engine rebuild this summer)
http://www.vwspares.co.uk/g1filters.php

Use a genuine VW oil filter, you can get them from here or a VW dealer, they are about the same price from VW as in the link above.
Don't forget a new sump plug washer.

I now use this stuff as it's only £12.50 for 5L when on offer and meets the VW spec.
http://www.eurocarparts.com/ecp/p/car-accessories/engine-oils-and-car-fluids/engineoils/10w40-engine-oil/?521776011&0&cc5_245

Just found it on eurocarparts cheaper sister company for £12.49!
http://www.carparts4less.co.uk/cp4l/c/Volkswagen_Golf+Cabriolet_1.8_1989/p/accessories-engine-oil/engine-oils/engine-oil/10w40-engine-oil/?521776011&0&cc5_245

Sump plug washer, has the size in the link.
http://www.carparts4less.co.uk/cp4l/c/Volkswagen_Golf+Cabriolet_1.8_1989/p/car-parts/engine-parts/engine-parts1/sump-pans-and-sump-plug/?360440010&1&47e565edaab1b27f65ebe18b800a910f4348a294&000567

Nice info