I have just waxoiled my spider (actually Pro-Form) with engine cleaner wand and compressor. Mixed it 1 to 1 with turpentine, not the low smell type so stunk for a few weeks. Sprayed through the inside sill holes, taped them up then sprayed from holes below, then with headlights raised in through the wheel well parts, (you could see the mist coming out the bottom sill holes.
If your sills are particularly dirty I would flush them with power washer then dry with hair dryer. If there is some surface rust in there I would use ship-2-shore. They have a website. At $80 a gallon farely pricey but better than Blue steel at $120 a gallon. It reacts with rust, can be painted over, creeps into nooks and crannies, meant for marine salt water environments. Ozzies have similar product called PPW or some such. Better than welding and replacing sills down the road.
TR7 Spider - 1978 Spifire - 1976 Spitfire - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra
