So what brand of engine oil should I use? I looked at older RT's and the change was also made. BMW vehicles are designed to require service less frequently than other makes, allowing you more time on the road and less time in the shop. Buying a bike starts at Bikez Get a list of related motorbikes before you buy this BMW. Read the riders' comments at the bike's discussion group.And check out the bike's reliability, repair costs, etc. Look at photos. The oil seems to be coming from the bottom of the rubber flex boot between the swing arm and the final drive:, the end of the boot where it attaches to the swing arm. Show any 1998 BMW R 1100 RT for sale on our Motorcycle Classifieds. – 1998 BMW R1100RT. BMW R1100RT Specifications Start of Production 1995 End of Production 2001 Numbers Produced 54,751 Price 24,500 DM Engine Motor Type Four-stroke, two cylinder, horizontally opposed "Boxer" engine, air cooled Bore x Stroke 99 x 70.5 mm (3.89 x 2.77 in) Displacement 1085 cc Max Power 90 hp (66 KW) at 7,250 rpm Found a build up of black oil on the rear wheel after a ride. Inspect technical data. Manufacturer – Make – Model – Year: BMW R 1100 RT (ABS) 1998 Motorcycle Style: Touring . Transmission Oil Type for RT. Besides the argument over what type of fuel you should use in your BMW (we only use Shell 93 octane by the way), no other topic conjures up more controversy like the BMW engine oil debate does. I cleaned up the rear end and took it for a ride. ENGINE SPECS Engine Type: 1085 cc, 4 Stroke – Liquid Cooled – Boxer Twin Engine Bore and Stroke: 99 mm x 70.5 mm Valves 4 valves/cylinder Claimed Horsepower: 90 hp (67.1 kW) @ 7250 rpm BMW R1100S 1998-2005 BMW R1100S Boxer-Cup Replika 2003-2004 BMW; BMW R1100S 6-Speed (1998-2006) Engine ... A full synthetic four-stroke SAE 5W-40 engine oil suitable for use in high performance and competition four-stroke, Japanese and European motorcycle engines, including all high performance multi-cylinder, multi-valve, V-Twin, air or water-cooled sports or race replica models. 2005 and newer use the same oil. 75W/90. If the BMW stuff is too expensive then use the Land Rover gear oil P/N LRN 7591. Bimmer drivers get to avoid the 3,000 mile oil change and instead only need an oil service every 7,500 miles for their Intermediate Oil Change and Oil & Safety Service appointments.. How is oil for BMW vehicles different from oil used in other makes? MANUFACTURER SPECIFICATIONS. We have watched friends lambaste each other on forum threads over the issue. The best oil for a high mile 1998 323 is 15w40 if you live in a new England type climate with cold winters as nd hot summers, it came with non synthetic so there is no need for synthetic as long as you change the oil often. I'm sure it had been building up. It seems to be light weight oil.