Cleaning sludgy nissan VQ

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So, here is the story: purhaced a car off lease with about 34k on the clock. Things appeared ok at purchace (clean dipstick, no crud visible from the oil fill. Shortly after purchace it started occasionally blowing a cloud of smoke at startup. Dealership ran a compression test and all was good. Techs were baffled and generally unhelpful. I managed to figure out that the PCV passage in one of the valve covers was gunky and not draining well. As oil mist co densed it was retaining a pool of oil that was getting sucked into the PCV on startup. Blasted it out, cleaned the pcv, no more smoke, no more oil consumption. Was thrilled ot wasn'trings or valves but suspected the former lessee was less than dilligent about oil changes. Switched to M1 synthetic figuring it will slowly clean and all was well.

Fast forward another 25k mi and i get a check engine light for low oil pressure and camshaft timing. Dealerhip finds a blown oil gallery gasket (not uncommon) and goes to replace under warranty. Turns out the engine is kinda gross inside an and the gallery is sludgy, as is the cam actuator.

I think my slow cleaning with M1 is starting to break things loose. Dealership has replaced the front timing cover, timing chain and tensioners and one of the VVT actuators that was failing. They also cleaned up that area of the engine and the oil pan and pickup.

I'm left with a connundrum. Do i keep slow cleaning and risk more crud breaking lose elsewhere in the engine or do a hail mary with a fast flush to try and clear out as much as i can, then continue with short OCIs?
 
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I think I'd go with some PYB or some Maxlife syn-blend. A full syn in a possibly neglected engine, no thank you, way too risky for me.
 
Originally Posted By: SatinSilver
I think I'd go with some PYB or some Maxlife syn-blend. A full syn in a possibly neglected engine, no thank you, way too risky for me.

+1
 
I think the M1 got me to this point by breaking up some of the sludge. I wouldnt call it possibly neglected either. Despite a half dozen M1 changes in the last year, i got a look at the timing cover and, while I've seen worse, there was definitely a good amount of varnish and some sludge in the less oil washed areas. No hard deposits evident, just tar-like gunk

On the bright side, the entire timing cover and associated galleries are brand new, as are the vvt actuators. The front cover, oil pan and pickup have been manually cleaned. My only concern is that deposits elsewhere in the engine will break loose down the line and again plug one of the billion tiny oil passages in the complicated valvetrain and i wasnt sure if a flush would get it out or just loosen it up more making things even more precarious.
 
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The VQ motors are not great long run interval oil change motors. With only a shade under 5 qt capacity they don't have much in terms of extra capacity to help keep oil temps down and not as much containment holding capacity either. This is compared to other motors that have 6.5 qts plus. I hope this all gets a whole lot better for you.
 
I'm aware. 3750mi recommended oil changes. The heat and friction from the VVEL system and a 7500rpm redline also shears oil like mad, which is why i was using synthetic and would like to continue if it is safe to do so.

I don't think the engine design was the problen as much as a lessee who didn't see the point of changing oil on a "rental car"
 
I've used Amsoil Engine and Transmission flush in the last 5 used vehicles I've bought and never had any engine issues.

http://www.amsoil.com/shop/by-product/ot...?code=FLSHCN-EA

If your engine still exhibits some sludge after 25K of M1, I would do an engine flush. The Amsoil product is a detergent, not a solvent, and extremely unlikely to break off big chunks of anything. Besides, by your description you don't have big chunks of anything anyway!
 
Originally Posted By: Bluestream
Slow and steady Son, that will get you where you want to go.


Welcome to the board.

+1 on the above and the recommendation for PYB or even Quaker State. You don't mention the year and model. In my wife's M35 I used Kendall synthetic blend for the first 65K miles. I have stuck to oil changes of 4,500 miles. For the last 30K miles I've used my own blend of 40% Quaker State Ultimate 5w-30 and QS conventional, and the engine appears clean and runs quietly. When I changed the PCV valve at 93K miles, it was quite clean.

To clean you may also want to try Pennzoil Gold 5w-30 at Walmart for about $17 a jug. I now like the Fram Ultra filters for this engine, or the Fram Pro Synthetic Series you can find on eBay.
 
I would just continue using synthetic with reasonable OCI's. I've seen more than a few examples of leased cars where the oil was never changed. When we recently bought an off-lease vehicle, I pulled the valve cover and inspected before we finalized the deal. (it was spotless inside) Of course, I have friends who don't change oil in the cars they have purchased, so its not limited to leases, but likely much more prevalent.
 
Well, a picture is worth a thousand words. This is the engine with the front cover off prior to the rear timing cover and components getting replaced



Back of front cover (since cleaned)



The most baked on stuff found was still tarry, not coked



VVT actuator (since replaced)



I'm sure you can extrapolate as to what might remain elsewhere in the engine.
 
Originally Posted By: vitez
I've used Amsoil Engine and Transmission flush in the last 5 used vehicles I've bought and never had any engine issues.

http://www.amsoil.com/shop/by-product/ot...?code=FLSHCN-EA

If your engine still exhibits some sludge after 25K of M1, I would do an engine flush. The Amsoil product is a detergent, not a solvent, and extremely unlikely to break off big chunks of anything. Besides, by your description you don't have big chunks of anything anyway!


I agree, using a flush designed for use at idle would get the block clean far faster than just doing short OCI's with a good cleaner oil.
 
Yeah, I was complacent since it was such a young car and the parts i could see through the oil fill werent even varnished. I suppose a shady car dealer could have blasted anything visible away with carb cleaner and put clean oil in.
 
Originally Posted By: UltrafanUK
Originally Posted By: vitez
I've used Amsoil Engine and Transmission flush in the last 5 used vehicles I've bought and never had any engine issues.

http://www.amsoil.com/shop/by-product/ot...?code=FLSHCN-EA

If your engine still exhibits some sludge after 25K of M1, I would do an engine flush. The Amsoil product is a detergent, not a solvent, and extremely unlikely to break off big chunks of anything. Besides, by your description you don't have big chunks of anything anyway!


I agree, using a flush designed for use at idle would get the block clean far faster than just doing short OCI's with a good cleaner oil.


Just concerned something like that will send any remaining sludge right back into the problem areas that were just cleaned or replaced. Most of them have warnings abot using on heavily slidged engines and I dont know what they consider "heavily sludged"
 
I hope you got a heck of a deal on this car.

I would suspect that you will have carbon on the rings and all kinds of fun in the upcoming miles.

If it were mine by looking at the pictures i would try to get out of it...or invest in an extended warranty.
 
Originally Posted By: vitez
The Amsoil product is a detergent, not a solvent, and extremely unlikely to break off big chunks of anything.


Granted, my HazMat certs expired years ago, but the ingredients certainly read like a laundry list of organic solvents. Not saying that makes it dangerous to use in a lot of circumstances, I'm just concerned about what it doesnt completely liquify and wash out in a legitimately dirty engine.
 
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Originally Posted By: krismoriah72
I hope you got a heck of a deal on this car.

I would suspect that you will have carbon on the rings and all kinds of fun in the upcoming miles.

If it were mine by looking at the pictures i would try to get out of it...or invest in an extended warranty.



I've had the compression checked and it's perfect in all cylinders.

Extended warranties are no help to me. I put on too many miles to get any value from them
 
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Did the dealer who sold it to you disclose the lack of oil changes? If they knew I'm sure the former lessee/owner paid bigtime . Then the dealer goes and sells it as mint condition..... I would be livid!
Hopefully you got a steal on it...
 
Originally Posted By: Brybo86
Did the dealer who sold it to you disclose the lack of oil changes? If they knew I'm sure the former lessee/owner paid bigtime . Then the dealer goes and sells it as mint condition..... I would be livid!
Hopefully you got a steal on it...


Got a good deal, but its a used car dealer. Caveat emptor. My problem now.
 
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