Jemma - I am using 50 also and it is dry. I notice the engine is a little noisier also, the parts are not as covered with oil. You are correct in your noticing that the wash spots are not the same, just a Chinese engine with a little man making up the sand molds, doing the best he can. No worry these engines are so crude there is nothing that matches. Just a little note. I am a member of the Ford model T club. We had a member that discovered that the original engines had no indexing of any parts, (IE) some pistons were up higher than others and the cam, well we need not talk about that. He fixed it and do you know what he got? A model T that sounded like a modern car, that was no fun. I think it gives these things a little character, besides one of my ears is a little lower. Have fun, Dave