That’s a pretty loaded question, and does’t have on singular definitive answer. Read any auto forum and you’ll get 100 different answers. Here are our thoughts on the subject, taken from reputable sources, and professional engine builders we work with.
Mineral Vs. Synthetic: Touchy subject with much debate online – but our primary engine builder recommends mineral based oil for “old school” engines – it’s what they were designed to use, and you can’t go wrong. In particular – we have been using both Driven Racing Oil (no affiliation) based on this recommendation – In particular their conventional hot rod oil (HR2). It’s enhanced with the zinc additives that in the last decade have left most off the shelf oils (read more about that here). We’re also fan’s of Redline Oil as they are in our neighborhood and make some great products. You’ll find both brands stocked in the shop.
If we’re talking about an LS swap, Hellcrate or modern engine in a late model, we rely on factory specs oil – and our favorite brands have options for them as well.
Whatever your thoughts, or your buddy on the forum’s thoughts are – one thing we can generally agree on is to stay away from quick oil change places for your Classic Car, Muscle Car, Restomod or specialty car. You’re going to get a low wage employee who doesn’t care pumping who knows what into your engine while stripping out your drain plug, and up-selling you services you don’t need. Pay a few dollars more – we’ll take care of your baby right.
Interval is another factor – Our rule of thumb is every 3000 miles – or if your car is an occasional cruiser, only seeing infrequent weekend use – then 2x per year – usually a the start of summer cruising season, and a few months before you put your ride to sleep for the rainy season. Engines are expensive – and frequent changes help keep everything lubricates and most of all remove contaminants and dirt from the oil.