{Bolding mine}
Your English is very good, but it’s the little things that are tipping us off. Here’s how your sentence would be written by, well, me.
“Do I have to watch more sitcoms and read more paperbacks to make sure that my English is good enough to pass the watchful eyes of the language police?”
Nope. I put a ton of miles on the vehicle, and the vehicle is co-owned by me and my business which is a sole proprietorship. My accountant says to do it this way, and she has never steered me wrong yet. 
Ah, you’re depreciating the full cost of the vehicle. Nicely done.
Water Jacket and corrosion? The only thing I get out of that is the freeze plugs went south. Anyone?
My car’s 15 and I’ve replaced the radiator twice. The second time I did the job myself which was an interesting learning experience if nothing else.
Just sayin’, is all.
Hell, I bought a '91 Nissan Stanza in December for $800 at a used car lot in Chicago. Haven’t had a major problem yet–just needed to replace the alternator–whopping $150 repair. 
I say you can’t go wrong with an old Toyota or Honda. I know plenty of people with mid-80s models that are still going strong.
I’m thinking axle boots?
When I first read it I thought WTF??? 
But I am sure that Uncommon Sense showed uncommon sense by figuring out that it was the freeze plugs (soft plugs, core plugs, frost plugs etc)
Sorry Hello Again but there is no water jacket on the axle boots.
The OP doesn’t live in the US, nor is English his first language. I was thinking “water jacket” is a regionalism or translation of what we call the Axle Boot. After all, there are four of them and they protect an important part (the CV joint) from grit and corrosion as alluded to by the OP.