I've only owned my 1990 since April last year but have put on 19,000 km since then to bring it to 110000km. It still has the 28A alternator, and I have carefully cleaned and greased all connectors, and there are no signs of any heat-related damage. I suffer from maintenance OCD. It has always has a slight oil weep from the end cap, enough to be visible on the casing but not enough to drip off. I have a voltmeter installed and have moved to all LED lighting, with just heated grips as farkles, and the voltage is rock-solid at around 14.2V.