I used Castrol GTX 20W-50 in a 72 VW Super Beetle I bought new. I changed it every 3,000 miles. At 101,000 miles a valve stem broke. The mechanic who rebuilt that engine was also a friend of mine. I asked him to mic out wear points because I wanted to know how much it had worn during that 101,000 miles. Later he told me the engine throughout was within specifications of the car when it was new.
When I got the car back from him I asked how he wanted me to break it in. He wouldn't give me any information on wear in. I asked him if it was his practice to rebuild engines and to refrain from telling the customer how to break it in. He told me he always gave such instructions to all his customers, except for me. He told me that whatever I had done with that car when I bought it, "...just do the same thing again". I drove that car another 200,000 miles, still using GTX 20W-50. Compression checks showed all four cylinders remained up to spec throughout that time.
After all that use for 21 years I sold it for 80% of what the car cost me new.
Havoline 20W-50 (I don't remember seeing it) might would have done me just as well, but the Castrol GTX 20W-50 certainly didn't me in any way.
