OIL.....switch from conv. to synthetic?

[redrob]

Ok so I want to start possibly using synthetic oil (blend or full) to lengthen the amout of time and money spent on oil changes. I have always used conventional oil and have changed it out about every 3 to 4.5K miles. I could not find the thread but read switching will have the advantage of longer intervals between changes and better protection. 95% of my driving is highway (65-85mph) driving and my main concern is if there is any possible dangers to just outright switching to synthetic. I dont know how much synthetic oils cost either so IDK if this would outwiegh the advantages either. Help a brother out.

[Daox]

There are no issues with just switching to synthetic. It'll increase power and gas mileage slightly (read: almost immeasurably) too. Synthetic does cost more, probably around 2X the cost, but you can easily go 3X the miles on it. I'd recommend getting an oil analysis done if you plan on going over 10k miles between changes though (which is quite doable).

[paulsaveo]

Some new toyota vehicles are designed for only using synthetic, on these toyota vehicles, toyota honors warranty for 10,000 mile oil changes. switching to synthetic in most cases is not a problem at all. it is not recommended on higher mileage engines (to switch). even though synthetic oil does not break down as quick as conventional, it is a little thinner. switching to full synthetic if your engine has decently low miles youre good to go

[redrob]

Currently my car has 68XXX miles on it so I guess it on the high side.

[Daox]

Nah, thats pretty low. I'd bet it'll be fine. The only issues are due to leaking/burning. Try it out and just watch for leaks after a week or so.

[redrob]

Where would leaks be most prone after switching? I assume the oil pan and possiblly the manifold and heads? Also would you guys suggest going with a blended syn/conv for the first change then fulll synthetic after that. I just dont want to screw up my (lawnmower)engine doing this.

[Daox]

Honestly, I'd just put full synthetic in and not even worry about leaks/burning. Check the oil after a month to see how much the level has dropped. I really doubt you'll have a problem, and even if you do, its not gonna screw up your engine.

[petrified.rabbit]

the only reason i can see synthetic causing leaks nowadays is from it washing away the build up (sludge) from conventional oil.

but you would need more miles and have a bad oil change history for that sludge to be that detrimental.
I think for your first synthetic oil change, even with less than 70k miles would be the change it early (like 3000miles) again just to get the "washed" conventional out of there. But if the conventional is sludged enough to cause problems when you put synthetic in, i would guess you would clog something and leak before making it to any kind of maintenance interval.

[paulsaveo]

the only reason i can see synthetic causing leaks nowadays is from it washing away the build up (sludge) from conventional oil.

but you would need more miles and have a bad oil change history for that sludge to be that detrimental.
I think for your first synthetic oil change, even with less than 70k miles would be the change it early (like 3000miles) again just to get the "washed" conventional out of there. But if the conventional is sludged enough to cause problems when you put synthetic in, i would guess you would clog something and leak before making it to any kind of maintenance interval.

I definitely agree with rabbit on this one, hence the reasoning to me mentioning high mileage. 68,000 you should be fine unless youve had quite a few over mileage oil changes. on higher mileage engines, they are morelikely to have sludge or build up along with piston rings that may have slight wear, which when you add a thinner synthetic, it can break up sludge and buildup making it easier to seep around piston rings and through valve guides.

[petrified.rabbit]

honestly, it is not thinner.. it feels that way on your fingers because of the lack of wax, but the viscosity is the same.

and i've seen 40k miles engines seize from sludge issues while running full synthetic since new.. (i owned one). And i have seen engines with conventional oil with 250k miles with no build up when you pull the valve covers. Its all about maintenance interval, the 40k mile engine recommended every 10k, and it obviously wasn't often enough. even though the oil was "ok" for that, it should have been done every 5k even with synthetic. The 250k mile engine was changed right before 3k every time and was as clean as new inside and out.