I have only ever used 10w40 semi, It is one of the recommended oils for this engine, It was recommended to me to use it by 2 main dealers, 2 of the UK's leading Vauxhall/Z22SE tuners and a race engine builder. Maximum of 5000 miles between oil changes as well. Proof is in how well and how clean the engine is. I only took my engine apart due to a cracked head (went to a bad tuner for a remap and they checked plugs with a hot engine. They also told me running 10w40 would kill the engine :ROFLMAO🙂 Chain was still spot on and no noise at all, all measurements still well within factory specs.
It is possible to drill holes in the oil control ring grove of the piston but I don't see the need for this, only reason the rings gum up is use of wrong oils, poor fuel and poor servicing.
There was some people on here with Z22SE engines that had gone way past 350,000 miles without any engine work.
The Z20LET does have a bad reputation for burning oil and stem seal failure. Again a lot of this is down to poor servicing then use of cheap parts when seals are replaced.
