Comments on: Semi vs Full Synthetic?

By: Greg Reed

Greg Reed — Mon, 27 Apr 2009 21:46:31 +0000

My personal recommendation: Go with synthetic, but keep to the dealer-recommended change intervals. I have a 2004 Forester XT. At 7500 miles, I switched to full synthetic. At that point, I started changing the oil *filter* every 3500 miles, and changing the actual *oil* every 7000 miles (every other filter change). I was told by numerous car-knowledgeable people that this was more than sufficient — most questioned why I didn’t just do both every 10k miles. I believed I was being over-cautious, and that’s exactly what I wanted.

Well, at about 95k miles, I lost my turbo due to poor lubrication. The tiny oil supply line has a strainer in it, which plugged up with sludge. The sludge resulted from — you guessed it: Not changing my oil often enough.

Turbochargers are very demanding in the lubrication department. The temperatures and RPM’s are far higher than encountered in most normally-aspirated engines. If longevity is important, I advise going to extremes to keep them properly lubricated.

By: loop

loop — Wed, 25 Mar 2009 03:33:04 +0000

Oops…did I say 10w-30…it was actually 5w-30

By: Chuck2001

Chuck2001 — Wed, 25 Mar 2009 01:28:44 +0000

My 2 cents…stay on semi-synt. You will change more frequently and in my mind that is a better peace in mind than full synt. Oil is the blood of the engine, and even synt is “better”, I prefer to change it at a frequently rate…

BUT ! Synthetic is better, will keep its viscosity (?), will stick to metal easily, will fill better all the parts, the metal parts will slide better into them, better performance (not noticable).

If you go this way, you will have to STAY synt…no coming back. I know some taxi drivers here in montreal that have made more than 100k KM without changing the synt oil….

Costly but better performer and you will have to change it at like 20-25k KM. If you drive a lot and the dealer accepts it (ask Subaru, they could even refuse to honor the warranty).

At last, little tips to know if an oil change is required. Don,t just check the color of oil…it is normal to have “black oil”…the engine is working you know. You have to notice the texture of the oil…is it too liquid, too solid (viscosity is the key). Another good one is the smell…if it smells like burn stuff, time to change it !

So, for the planet, don,t change oil too frequently, and synthetic is a choice…plus and minus comes with it. If you live in winter as well, it could be easier for the engine to have synthetic oil.

By: loop

loop — Tue, 24 Mar 2009 21:53:50 +0000

Took my ‘09 WRX 5-door to the dealer for it’s first service (oil/filter change and fluid level/tire pressure check) as well. Asked for specifics on what type of oil came in the thing from the factory and what the dealer would be using. The service manager said that Subaru doesn’t recommend synthetic and that this holds true for the STI as well. I’m currently in Florida for the season and will be going someplace warm for the summer as well, so they used 10w-30. A brand the guy said Subaru gets (couldn’t produce the brand name because I don’t think he knew. I guess the oil says “subaru” on it?!? maybe it does?…)