High Mileage Oils Help Stop Small Leaks ?

ZeeOSix

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Anyone have success on using a High Mileage oil with respect to stopping small oil leaks? GF has a G35 Infinity with 165k that has a small valve cover leak, and the valve covers are a royal pain to get to on this 3.5L V6. Was thinking of using "Valvoline High Mileage with MaxLife" next oil change and see if it helps. Anyone seen a high mileage oil actually help out with something like a slight valve cover leak?
 
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MaxLife has helped with a few that I had small leaks with-my 210K+ mile Jeep 4.0 had a small RMS leak that VML pretty much stopped, and my 200K+ 5.7 Suburban went from 1 quart every 600 miles to around 1 every 1500. Not saying it’s a permanent fix, but if it’s slow, and the leak is a PITA to fix, MaxLife is a cheap repair. ATP-205 is pretty good stuff too.
 
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Nope.

FYI - It will need both valve covers (not just the gaskets) because the tube seals are permanently installed into the valve cover. The job isn't very difficult but the cost of parts is around $450. I assume she has the DE?

Would there be any problem buying an after market brand that's like a quarter of the cost over the OE?
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ZeeOSix

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Nope.

FYI - It will need both valve covers (not just the gaskets) because the tube seals are permanently installed into the valve cover. The job isn't very difficult but the cost of parts is around $450. I assume she has the DE?

Yes, it's the 3.5L V6 VQ35DE. Ouch ... what's Nissan/Infinity thinking ??
 
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My mom's Five Hundred was using a quart every 1500 miles or so with Motorcraft semi-synthetic, and last OCI it used a quart in 2700 miles with Supertech conventional high mileage. Main leak on her car is valve covers and they're a pain to get to.

My car (2007 Ford Fusion) has a front main seal leak and it's had it since I got it, Valvoline Maxlife seems to be slowing it down but I can't say anything of the before mileage as it's on its first OCI, but the spots it leaves behind are smaller.
 
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Anyone have success on using a High Mileage oil with respect to stopping small oil leaks? GF has a G35 Infinity with 165k that has a small valve cover leak, and the valve covers are a royal pain to get to on this 3.5L V6. Was thinking of using "Valvoline High Mileage with MaxLife" next oil change and see if it helps. Anyone seen a high mileage oil actually help out with something like a slight valve cover leak?


Is it the front or back valve cover leaking??

If it is the rear one leaking then just replace the valve cover and... Those 3 back spark plugs too. Might as well while that cover is being replaced.

If it's just one leaking... You could have just the one valve cover replaced.

I have 332k miles on my VQ with the original valve covers still on there.
 

ZeeOSix

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Is it the front or back valve cover leaking??

If it is the rear one leaking then just replace the valve cover and... Those 3 back spark plugs too. Might as well while that cover is being replaced.

If it's just one leaking... You could have just the one valve cover replaced.

I have 332k miles on my VQ with the original valve covers still on there.
The 3.5L VQ in the Infinity G35 is not transversely mounted since the G35 is rear wheel drive - so it's left and right valve covers if standing in front of the car. I think it's both valve covers leaking a little bit.

The intake manifold covers most of the valve covers. I might try to see if I can check the cover bolts if I can get access to any. Otherwise, will probably try some Valvoline High Mileage for awhile and see what happens.
 
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Is it the front or back valve cover leaking??

If it is the rear one leaking then just replace the valve cover and... Those 3 back spark plugs too. Might as well while that cover is being replaced.

If it's just one leaking... You could have just the one valve cover replaced.

I have 332k miles on my VQ with the original valve covers still on there.
G35 is a RWD car
 
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Anyone have success on using a High Mileage oil with respect to stopping small oil leaks? GF has a G35 Infinity with 165k that has a small valve cover leak, and the valve covers are a royal pain to get to on this 3.5L V6. Was thinking of using "Valvoline High Mileage with MaxLife" next oil change and see if it helps. Anyone seen a high mileage oil actually help out with something like a slight valve cover leak?
I'm nearly in the exact same situation. My 08 quest has developed a small leak in the rear valve cover. I'm kicking myself for not changing it since i just had the thing apart to change the plugs and pcv valve. My tube seals weren't leaking and I didn't notice any leaks so I left it alone. I did decide to retorque the bolts while I was back there, i think that was a mistake. I also just changed it to M1 0w40 from whatever the guy before me was using so maybe that contributed. I've got some M1 HM 10w40 on the shelf that I'm going to try next. Its not a bad leak but I do get a whiff every once in a while..

I had another quest that I just changed the rear VC on last year, I used a Dorman. It just started to leak again however.
If i done it again I guess I would go with the oem. The price of those contribute to my hesitation to try this job again. Hoping the M1 HM does the trick on the 08
 
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I’ve had good results using Liqui Moly Motor Oil Saver in the M42 in my 3er as well as the N12 in my Clubman.
 
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My impression has been that high-mileage oils might help reduce leaks of seals that seal against rotating parts, but not leaks of gaskets (or sealant goo) between fixed parts. True or false?

High mileage oils contain seal swell agents. As seals age, they become less elastic and can shrink dimensionally.

Seal swell agents reverse this trend, making the seal more elastic (lower durometer) and causing them to expand dimensionally.

If a seal is non-elastomeric then seal swell agents aren't going to do much. Some static seals may be non-elastomeric, but many are. Particularly in more modern cars. So I don't think you can say they won't help across the board. It will depend on the composition of the gasket. Valve cover seals are generally elastomeric these days so they may be helped by a high mileage oil. In the old days they might have been cork or cork/rubber but I haven't seen those in a long time.

Silicone rubber gaskets are probably a special case and I suspect they aren't improved by HM oils. Those are pretty common on valve covers as well.

Seals on rotating surfaces pretty much universally have some elastomeric sealing surface and should be improved by seal swell agents if they've hardened and contracted.
 
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