Switching to synthetic after 40,000 miles?

[ColonelPanic]

Just curious about something... The Vibe is due for another oil change, the first it's needed since it was at the shop for that nasty cold engine knock.I've considered switching to a synthetic to see if that would help quiet the engine down a bit. Would running a synthetic be a bit easier on the engine when cold? I'm thinking so, it doesn't thicken as much as a conventional oil would when cold, right? Obviously, switching to a different oil still doesn't solve the problem my engine has. I really need to get the car back to the dealer for this, but they'll probably end up clueless about it like the last time. And, since I've ran conventional oil in the thing for the first 40K, would I be setting myself up for more problems by switching to synthetic? Would that damage the engine? er, that question should be worded "Would that screw it up any more than it already is?" lolThanks for any input you may give this oil-illiterate guy.

[Flip-Side]

Despite what you may hear all over the internet from snake-oil salesman and riceboys, you can switch to synthetic anytime. You can even switch between synthetic and regular oil whenever. Even mix the two together if your oil is low and you use what is available (but you will lose the synthetic benefits). Synthetic will simply protect your engine better...longer...and at startup, and will do all that better if you always use it.As far as quieting your engine, the more viscous synthetic oil will not help at all. I have never noticed a difference in sound between regular and synthetic, unless switching from 5w30 to 10 or 15w30. Though I will always use 5w30 in the vibe.Ever hear of motor honey? It was super thick oil you put in to quiet knocking and smooth out the engine. Of course it only made the problem worse by using that stuff.

[tecton]

i always heard use a 5 weight in the winterand a 10 weight in the summermabye thats backwards?

[futseal04]

You could, but I would recommend just using 5W-30 all year round. That is what the mfr states that you should use, and the 5W/10W issue is from years ago when mfr's stated that you had to change oil depending on the season. It was usually 10-40 in the summer, and 5-30 or 10-30 in the winter.All the numbers mean is how viscous the oil is. The 1st number is how viscous it is when cold, and the 2nd is when warm.

[ragingfish]

If you put 10W-30 in, and something happens to your engine that can be traced back to having put that oil in, Pontiac will wash their hands of the issue.If they tell you to use 5W-30, use 5W-30. Oil is one thing I'm not willing to take my chances with.

[ColonelPanic]

Yep, I've always stuck with the recommended 5W30 for each oil change... I think I'll go ahead and make the switch to synthetic at the next oil change..I'm thinking it probably won't hurt anything, the engine is pretty well screwed as it is.

[ToolGuy]

Nope will not hurt anything to switch like others have said. And I always use the recommended 5W. I look at it this way, it was designed for 5W and 5W was used for the best fuel economy. I always use what weight is told to use and never had issues.

[tnpartsguy]

Switching to a full synthetic before a 100k miles won't hurt, but is it neccesary? I use a semi-syn oil, Valvoline. Changing to a full Syn AFTER 100K can cause problems, we've seen many cars that come in with leaks, ect, and its where they have changed to a full syn after 100K. My euro-tech (he's certified on every High line Europeon car made) that switching from Dino to Syn after 100K washes the seals out, so he does NOT recommend it. Another point he made, the reason the Corvette and other high line cars need Mobil-1 is because they have harded-graphite rings, unlike the rings in a 'normal' engine. Just fact to keep in mind, IMHO, you'd be better off with a blend, the best of both worlds!!

[ColonelPanic]

I think I'm gonna go ahead and switch. Why not, right? Probably will be using whatever the dealer has, I'm guessing Mobil One. Not going to be cheap, but I'm wanting to give it a shot to see if it makes any difference.