What Earl said.
Semi synthetic is perfectly OK. I use 5-40 or 10-40.
If you tend to do track driving or don't change your oil often, fully synth might be better in that case. The downside as Earl mentioned, fully synth tends to find poor seals more easily and you will see leaks from the heads and around the drive pulley seals.
You can't go wrong with the semi synthetic Ahmed.
Joe
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