Graham cracker crust too salty for cheesecake

It's certainly safe. Butter, Oil, whatever, it's more about taste than anything else. Some people even push lard and butter as the "safe" options, because they require less processing than oil, and much less than margarine.

One thing which you should be aware of in regards to butter vs oil: butter has a significant amount of water in it, so you shouldn't substitute 1-to-1, or you will have a stronger flavour (and more fat) than perhaps you want.

If you're accustomed to salted butter, adding some salt will help ease the transition. If the flavour of olive oil is off-putting, there are plenty of more neutral flavoured oils that have a similar fat composition, or you can simply avoid extra virgin olive oil*.

*extra virgin olive oil in the U.S is largely a scam. In most of the world (countries that adhere to the IOC standard) this signifies "First Cold Press" olive oil. In the US it signifies "lamp grade olive oil with green food coloring". There are no restrictions on the use of terms like "extra virgin" in the US, so you can't guarantee that's what you're really getting just because it's on the label.

The UK supermarkets have the opinion that British people like milder garlic, so most of the garlic you find in the UK supermarkets, even organic garlics, are of a very mild variety. Also, they are bred for yield, in softer soils, so they produce bigger bulbs but less strong.

Garlic found in most French and Italian stores is much stronger, as that is what people demand. It is usually hardneck, rather than softneck garlic, and hardnecks tend to be much stronger. French garlic is usually grown in stronger soils, so it produces a stronger flavor.

My solution is to grow my own, 3 bulbs planted usually yields a years' worth of garlic for me, and because I have clay soil it has a strong flavor. It's by far the easiest and most rewarding thing I've ever grown.

If that's not your cup of tea then ask a greengrocer to stock a stronger variety of garlic, or order it from an Isle of Wight supplier. Of course, you could just use about 4 times as much to get more flavor.