Semi synthetic vs regular which is better?

Honestly I've switched between conventional, semi-synthetic and full synthetic in every one of my personal vehicles and never had an issue with leaks. I'm one of those guys who runs every possible mile out of a vehicle before replacing. None of that trade in every 3 years BS.

I had an LS engine go over 300k. Never replaced a single seal or gasket on that engine and I ran conventional oil in summer and full synthetic in winter. Not so much as a sweat or hint of a sweat anywhere on that engine when I sold the pickup.

 

some good suggestions here but more important than switching oil types are the change intervals. the more experienced know that u change oil when it gets dirty and contaminated and not from time or miles. first oil change should be very soon. after that change it when it gets dirty and that changes with miles. dirty oil carries numerous types of contaminates that are destructive to rotating assemblies. carbon(the black in oil) is very hard and when it gets in between 2 moving parts bad things happen. of course the harder u work the engine and the hotter u run it naturally shortens oil cycles. when u get a lot of loads in flat areas and loads that are light oil will last a lot longer before needing a change. synthetic or a blend is more forgiving to abuse like running hot and tends to be a little thinner so easier on starts in the cold. synthetics do tend to swell seals and stop minor leaks but will create all kinds of leaks if u switch back to regular oil after using synthetic because the seal loses the ability to retain sealing tension and size. synthetics also are able to accept a much more agressive additives package than standard oils. oil will virtually last forever if it never gets contaminated or dirty.as time goes on and miles stack up ring wear adds greatly to contaminated oil. hope this helps