High Mileage 1MZ-FE - From Synthetic back to Conventional Oil?

[OceanView]

My 98 ES300 has 291,500 miles on her and she's leaking a little oil.
I would like to know if it's ok to change back to conventional oil after using synthetic for over the last 200,000 miles.

No sludge issues but I wonder if changing back would encourage this.

[PortugalFocus]

Yes, swapping back and forth between conventional and synthetic is no issue at all.

[Eye8Pussies]

wouldn't be surprised if the oil leaks stopped once you switched back

[JohnGD]

Try a high mileage oil like Valvoline MaxLife. It has seal conditioners that may help too. Where exactly is it leaking from?

Originally Posted by OceanView

My 98 ES300 has 291,500 miles on her and she's leaking a little oil.
I would like to know if it's ok to change back to conventional oil after using synthetic for over the last 200,000 miles.

No sludge issues but I wonder if changing back would encourage this.

[SirThomas88]

From what research I've done... switching back and forth between synthetic and regular doesn't have any ill effect, but what could possibly have ill effect is switching to synthetic on a high mileage engine in the first place.

Apparently something about the synthetic being slightly thinner, cleaning out any sludge which may be protecting your seals and then slipping through the seals and leaking.

Edit: I've also heard that this issue over synthetic possibly causing problems is less common these days due to better engineering of the synthetic oil currently on the market verses when synthetic oil was a new product.

[OceanView]

Originally Posted by JohnGD

Try a high mileage oil like Valvoline MaxLife. It has seal conditioners that may help too. Where exactly is it leaking from?

I think there are a few spots, valve cover and another spot on the back side of the engine near the firewall.
I was planning on doing some extensive work on the engine when it hits 300,000 miles next year so I'm trying to band-aid this leak for now.

[LynchburgCSI]

Originally Posted by OceanView

I think there are a few spots, valve cover and another spot on the back side of the engine near the firewall.
I was planning on doing some extensive work on the engine when it hits 300,000 miles next year so I'm trying to band-aid this leak for now.

If you're going to "band aid" this for now, MAKE SURE you check your oil levels VERY VERY often.