Depends if you have retained the original radiator in your Lotus (you want to protect the solder & brass) or if you've got an aluminum one . I understand that the major problem seems to be with the solder corrosion, with the older lead types being worse. First - silicate is an aluminum protector. Secondly - Today's "conventional" coolants are different (low silicate) chemistry than the old Prestone type high silicate coolants. Here is one article by Paul Weissler that states "conventional" coolant SHOULD protect copper/brass radiators better: http://findarticles.com/p/articles/mi_qa3828/is_200408/ai_n9453107/pg_4 Here's another article recommending G05 in copper radiators: http://www.csfimports.com/tech.htm#antifrz Here is one article that says NOT to use OAT in copper systems: http://www.aa1car.com/library/2005/us90554.htm . The Zerex site (excellent info) and the Texaco/Havolene site tend to point people towards the "conventional" coolant for all pre 1995 autos. There seems to be little info about G05 use in old vehicles - be catious, IIRC, "OAT" (organic based) may not be the best for old solder. In my '84 U.S. version with A/C I've retained my original radiator (only re-cored with an extra row & I cleaned & refurbed my fans nicely & put in a ROW "hot" otter sensor - always keeping things very cool, & I'm running a slightly higher boost with a timed fan & air to air intercooler). I'm using Zerex green (old fashion) here in Canada with approx. 50/50 distilled water (no tap water for me) of course keeping the system in top shape & fresh clean/coolant religiously. My temps, are always under 90 degrees celsius, never an issue in hot summer traffic. Not interested in "waterless" coolant, overpriced IMO, I just make sure I keep up on my coolant condition. Hope this helps