Maintaining someone’s collection can be a great opportunity, but there is a different way of taking care of cars that are going to be sitting for a long time, to ones that are constantly being driven. Also, the level of these cars can pose its own challenges.

1. When the cars get light dust on them from just sitting, as they will, try to touch the paint as little as possible. You might be doing this every week so you don’t want to introduce the option for swirls at any time. Just use compressed air like the Metro Blaster. Stay away from using detail spray for this. If you need more than compressed air, opt for a waterless wash instead like Optimum ONR.
2. Check to make sure the battery tenders are still attached and are on with a microfiber resting between the chord and the paint. You are not the mechanic but battery tenders can have failures and it’s an easy check to let the owner know. That way you can help avoid an issue if they want to take the care out for a drive, to a show, etc. Or if you needed to move for a deeper detail.
3. When washing, be careful of where water can be used. The rubbers on some old Porches for example can start to get very brittle and water will seem through them causing damage. Also in the engine bay, cars pre-1990ish weren’t all waterproof connections like they are now. Also if an engine has open individual throttle bodies, you’re not going to want to get water in there.
4. Try to use seat covers and carpet covers. Most of these are likely collectible and any wear and tear will reduce the value. The owner may not like to see them and you have to take them down each time, but it’s worth it.
5. Lastly, and most importantly BE VERY CAREFUL. Obviously, with any car you are careful and with an expensive car, you are even more careful because the cost of replacing it is higher. But when you get into some of these collections, it’s not a matter of the cost to replace, it can be a matter of whether it can even be replaced. For example, a Mystichrome Cobras. Have you seen those seats? You think if you get a small tear you can just get it fixed by an upholstery shop? No shot. So just buy another one right? Well, they only made 1,010 of them so good luck with that. Or something like a BMW M1, I mean an M1, not the small 1M. The rarest car BMW ever made, many of which were one off colorways. A repaint on that cuts that value down an extreme amount. So take extra time to eliminate any room for errors because you wouldn’t just be damaging someone’s car, you may be damaging a piece of history.