I think you should be ok with 87. Some people (like me) think that on older engines with higher miles, its worth running silghtly higher octane. Why? because the carbon deposits in your cylinder can actually take up enough room to make a difference on compression within your cylinder. Higher compression + low octane gas = pinging = knock = detonation = boom.
honestly, i'd say you're fine with 87. i run 91 in my stock 328. uneccessary? mabye. safe? forsure.
(dont run too high gas though, if anything i'd say run 89)
then again, what do i know
wait for someone else to confirm, i dont know anything about e21's specifically
I run a canadian led kit & hid kit company, if you have any questions about led headlights or hid kits in canada or would like to check out our products please contact me here: http://absolutehid.ca
Hot: 2001 Estoril M RoadsterZCP 19's michelin supersports, ZHP knob, JL 8W3
Cold: 2002 TiAg M3 6mt
deoranged, dechromed, led tails, ZHP knob, UUC SS v3, GROM, OEM 18's w310's,
Fun: 2006 YZF-R6, black, ohlins, pazzo, cat delete, vance hines csone, YEC racing tune