Recently got a 2006 Toyota 4runner with the v6 for my girlfriend. The 4runner was in great shape with 179000 miles on it. Guy had it since new and only ran conventional oil in it. Right when I got it I changed the oil to Shaeffers supreme 9000. Now 3500 miles later the rear main seal on the engine has started leaking. When we got it it was completely dry underneath and not even a hint of a leak. I've always herd to not switch to synthetic on higher mileage because it will cause leaks but I kinda just thought that was an old wise tale. Is it just a pure coincidence or do I need to go back to conventional oil in this?
2006 4runner Oil Leak After Synthetic
- Thread starter Lucas_Jones
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Just my opinion. There is no problem switching between conventional and synthetic but when a engine has been run on one type for a long time and the switch is made, leaks can develop.
I would go back to conventional but the leak might not disappear now. Consider Valvoline Maxlife
I would go back to conventional but the leak might not disappear now. Consider Valvoline Maxlife
Synthetics just clean out the trash and gunk from conventional oil that was laying between the seal and sealing surface base metal.
Going back to conventional oil may not really do you anything now that the Synthetic oil has flushed junk out of the seals.
I would try a high mileage oil that has seal conditioners to make the seals more pliable and that can reduce or stop your leak issue if not too far gone.
Going back to conventional oil may not really do you anything now that the Synthetic oil has flushed junk out of the seals.
I would try a high mileage oil that has seal conditioners to make the seals more pliable and that can reduce or stop your leak issue if not too far gone.
Call Bars Leak (same company as Rislone) and talk to them about your leaking main seal. I've called them a couple times over the years and they're really helpful.
My guess is they'll recommend something like this but it's worth the 10min call to get their advice. Be advised if it's a "bad" leak, no HiMi oil or OTC seal conditioner is going to stop it for too long...it'll eventually begin to leak again. Are you 100% certain it's the rear main and not a valve cover? On some vehicles a leaking VC can appear to be a main seal leak. If you're not 100% certain you can put in a UV dye to trace the leak.
800-345-6572 M-F 9-5pm EST
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My guess is they'll recommend something like this but it's worth the 10min call to get their advice. Be advised if it's a "bad" leak, no HiMi oil or OTC seal conditioner is going to stop it for too long...it'll eventually begin to leak again. Are you 100% certain it's the rear main and not a valve cover? On some vehicles a leaking VC can appear to be a main seal leak. If you're not 100% certain you can put in a UV dye to trace the leak.
800-345-6572 M-F 9-5pm EST
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At 179,000 miles you can't actually prove the synthetic oil did it. Might just be adding to the myth.
Originally Posted by Lucas_Jones
Recently got a 2006 Toyota 4runner with the v6 for my girlfriend. The 4runner was in great shape with 179000 miles on it. Guy had it since new and only ran conventional oil in it. Right when I got it I changed the oil to Shaeffers supreme 9000. Now 3500 miles later the rear main seal on the engine has started leaking. When we got it it was completely dry underneath and not even a hint of a leak. I've always herd to not switch to synthetic on higher mileage because it will cause leaks but I kinda just thought that was an old wise tale. Is it just a pure coincidence or do I need to go back to conventional oil in this?
The guy you bought it from did not do timely OCI and left the oil in too long so that it accumulated crud, which the new oil has dislodged.
I would also do another Oil Change Immediately so that that crud doesn't travel too far and block some other orifice.
Recently got a 2006 Toyota 4runner with the v6 for my girlfriend. The 4runner was in great shape with 179000 miles on it. Guy had it since new and only ran conventional oil in it. Right when I got it I changed the oil to Shaeffers supreme 9000. Now 3500 miles later the rear main seal on the engine has started leaking. When we got it it was completely dry underneath and not even a hint of a leak. I've always herd to not switch to synthetic on higher mileage because it will cause leaks but I kinda just thought that was an old wise tale. Is it just a pure coincidence or do I need to go back to conventional oil in this?
The guy you bought it from did not do timely OCI and left the oil in too long so that it accumulated crud, which the new oil has dislodged.
I would also do another Oil Change Immediately so that that crud doesn't travel too far and block some other orifice.
I've switched my vehicles (F150 at 181k, Ram Van at 160k and 4Runner at 245k) to synthetic with no extra leaks. The F150 rear main always had a small seep and when I switched to M1 HM 10w-30 it stopped. Might try a HM synthetic.
Thanks for the all the help everyone! What oil has the best seal conditioner package for high mileage engines?
My vote would be for maxlife
Read my post...
Originally Posted by Lucas_Jones
Thanks for the all the help everyone! What oil has the best seal conditioner package for high mileage engines?
There is no best here. Maxlife is considered the standard among high mileage oils. If you have a favorite oil company that makes a HM oil then that would be fine.
If on a budget, Chevron Havoline is selling a HM oil in their 6qt Smart Change box for $15.47 at Walmart. Can't go wrong there.
Thanks for the all the help everyone! What oil has the best seal conditioner package for high mileage engines?
There is no best here. Maxlife is considered the standard among high mileage oils. If you have a favorite oil company that makes a HM oil then that would be fine.
If on a budget, Chevron Havoline is selling a HM oil in their 6qt Smart Change box for $15.47 at Walmart. Can't go wrong there.
Originally Posted by Billbert
My vote would be for maxlife
I have a 2006 Nissan Pathfinder with 185k miles...always changed the oil at 5k intervals with Mobil 1 10w-30 synthetic. I was in NAPA and picked up their synthetic and did an oil change and got a leak around where the rear main seal leak would be. I changed after 3500 miles to Valvoline HM oil and leak has stopped. Not saying the NAPA oil caused it; just seem to happen that way.
My vote would be for maxlife
I have a 2006 Nissan Pathfinder with 185k miles...always changed the oil at 5k intervals with Mobil 1 10w-30 synthetic. I was in NAPA and picked up their synthetic and did an oil change and got a leak around where the rear main seal leak would be. I changed after 3500 miles to Valvoline HM oil and leak has stopped. Not saying the NAPA oil caused it; just seem to happen that way.
Try M1 5-10HM oil. Here is a link.
https://mobiloil.com/en/article/car-maintenance/learn-about-motor-oil-facts/high-mileage-motor-oil
https://mobiloil.com/en/article/car-maintenance/learn-about-motor-oil-facts/high-mileage-motor-oil
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Any leak can be caused by excessive crank case pressure. Check your PCV system.
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