All of what has been said so far sounds like good info for your friend. You might want to change your
oil a littel earlier this time as well. Once it's burned up it don't work as well.
I'va actually FIXED problems with one of my fox's by overheating it!
It had a minor sticking lifter for a few months. one day I was on my way out to a friends house and the car seemed VERY sluggish. About 7 miles and she just shut off. No signs of overheating at all. I didn't run a thermostat in that car. Well, i get it fired back up but it knocking like crazy and smoking on acceleration. "Only a mile to my friends.. i can make it!" The last stop sign before his house she shuts down and won't even turn over. "wonderful, what have I destroyed now?!" Pop the radiator......... NO water. ZERO, ZILCH, NADA! Not good..... She took 12 gallons of water, most of which steamed away. I'm thinking.. "I've welded the whole rotating assembly into a pile of junk!" Let her cool down good, fired her up and got to my friends. topped the water off and listened to her run... no lifter tap... SWEET! lol
This is not the method I would recommend to fix anything! I'm sure it did more damage than good in the long run!