Hey everyone.

Question, how long of a break in time (milage) is needed before you can switch to a synthetic motor oil?
And do you just drain, refill and go..... or is some type of flushing needed?

Thanks for any feedback,
Jim

 

On a fresh rebuild, I changed my oil right after a few hours of run time, then at 500 miles, and at around 3000 miles I switched to Castrol Synthetic.

That's maybe a little ****, because really, the rings should seat in the first hour or so if you follow the directions that come with your piston rings. It basically tells you to gun it and let off quickly several times at certain RPM's in order to seat the rings.

Cam break-in occurs in the first 1/2 hour or so.

Try a search, may help....


BTW, no flushing needed. Unless you're using some exotic oil.

 

Just to add one more thing....I'd personally put at least a couple thousand miles on it before I'd make the switch...

Just to be sure everything is seated and you have no leaks. Synthetic costs a few bucks more.

 

If your engine hasn't had full synthetic oil in it before, and has over 100,000 miles on it, DO NOT USE FULL SYNTHETIC. Use a part synthetic motor oil, I prefer "Castrol Syntec Blend". =)

 

Ok, shoulda caught that before.... since your wondering how long of a "break in period" is needed, i'm guessing it doesn't have over 100k miles.

 

¿? I'm confused...

 

me too---whats your reasoning?

 

If you haven't had a full synthetic motor oil in your engine for the first 100k miles or so, then the piston rings/other such parts have already gotten all the wear that they're gonna get. Switching to a more "slippery" motor oil will cause minor oil leaks, because it can more easily slip through the worn spaces on the rings, ect. Hope that helps.

 

I have never heard this before. Can anyone back up the validity to this. I have 148,000 miles and was going to switch to a synthetic don't know if its ever had synthetic in it before I have owned since 133k, should switching really be of any concern.

 

well, it won't damage anything, it's just not beneficial at all. I was gonna switch to full synthetic but was told by the guys at Baxter's, Schuck's, and an AEM certified mechanic, who is a friend of mine to not switch to full synthetic. Since my engine has 180k miles , I decided not to. The choice is still yours though, and the guys I talked to could just be full of ****... but I doubt it.

 

I kinda see where he's going...it's more like "don't bother using synthetic oil at this point." What're ya gonna do, prevent wear?? Too late.

 

You can prevent more wear...

 

the seals are a little more worn at that point and switching to synthetic oils will cause leakage.

 

Sure, but at >100K miles of dino juice usage it's kinda iffy about how much benefit you'll get. The bores and rings are nice and worn, big end-gaps letting blowby contaminate the oil, soot crud has accumulated in the splash areas, bearing clearances are opening up and making it tougher for the thinner synth oil to maintain a film

For me, they'll have to pry my Amsoil bottle out of my hands to get me to stop using it. That 15W-40 really holds up to a beating, and 10W-30 is great in cooler weather street driving.

And no, I don't sell Amsoil...I just beat the snot out of my car and check the magnetic drain plug and filter media.

 

My engine had 123k on it when it was switched over. It now has 157k, all bottom end seals are original (heads, obviously, are not). No leaks.

Within about 1k of switching over, I replaced the intake valve seals - reduced consumption dramatically. When I pulled the heads off for the mods, no significant ridge on the cylinders.

Back to the original question - you can switch a rebuilt engine over to synthetic as soon as the rings seat. A properly rebuilt engine will seat the rings easily within a hundred miles.