When I purchased my vehicle, I made the mistake of going with a company underwritten by Hollard.
I had an incident with my vehicle where apparently the oil cooler released oil into my water system and caused the whole system to create oil sludge in the water cooling system.
I tried claiming for it, but apparently, because the oil cooler was the cause of the issue, they would therefore not cover the repairs as the oil cooler is part of the exclusions list.
I went through my policy documents where it states the inclusions and exclusions and went through everything just to make sure I'm not missing anything and nowhere in the policy nor in the exclusions list was the oil cooler mention. It was not in the inclusions list either, only those parts that was damaged from the water cooling system was covered.
So basically it was a grey area and they could do and say anything they wanted to.
What I'm getting at is that I've now learnt from that mistake and what I prefer doing now is saving up my money and should anything major happen mechanically then I will just pay cash to have it replaced.