Under the Valve covers @395,000 miles Nissan Xterra VQ40

[SC Maintenance]

I finally got around to fixing the very leaky valve cover gaskets on my 395,000 mile Nissan Xterra. I bought this vehicle new in 2008 and I have always ran this on conventional or semi synthetic following approximately the factory recommended 3,750 OCI. Latest few runs have been on Chevron Supreme 5W30 semi syn.

Generally I am pretty happy with this.

I am confused however as the right side has a little bit of varnish, and the left side has really none? The PVC is on the right side, that's the only difference I can think of - unless it gets hotter over there or something?

Thoughts?

Left:

Right:

 

[loneryder]

Looks fantastic for non syn oils.

 

[WeyounDS9]

Nissan for the Win!

 

[proveitwithdata]

i think the varnish is from going over the magical 2000 mile oci that david from automotive press recommended.

in seriousness it looks great for 400k miles

 

[Overfill]

average speed, if you know?

 

[SC Maintenance]

average speed, if you know?

No clue, but it is a lot of highway, followed by a lot of idling when I arrived. It retired from work duty in 2019 at 352,000, so since then its been mostly local shorter trips, with a few longer trips mixed in.

 

[Soft Cars]

That one camshaft has "RE" stamped on it. Is that for Right Exhaust?

 

[CharBaby]

i think the varnish is from going over the magical 2000 mile oci that david from automotive press recommended.

in seriousness it looks great for 400k miles

I know right?
I saw that segment with the guy who owns a GT-R and maybe if you owned a HP vehicle like the GT-R and drove it like you stole it, you should change the oil every 2K miles.

SCMaintenance: The XTerra engine looks great!

 

[wemay]

That looks amazing for 400k miles, on any oil. Proof that Conventional/Blends are just fine at the appropriate intervals.

 

[SC Maintenance]

That one camshaft has "RE" stamped on it. Is that for Right Exhaust?

I presume now that you point it out. It is the one for right exhaust.

 

[ZZman]

Looks great to me.

 

[joekingcorvette]

It looks very nice and clean. Keep up the good work.

 

[gman2304]

Looks great! My family members have owned at least a dozen Nissans over the last 30 years and all have been extremely reliable, especially their engines. Yours looks like a good candidate for a half million mile goal. They don’t seem to get much Love on Bitog for whatever reason.

 

[atikovi]

I am confused however as the right side has a little bit of varnish, and the left side has really none? The PVC is on the right side, that's the only difference I can think of

Most likely. Seen that on a few engines before. And to those that suggest 10,000 mile oil changes with synthetic are perfectly fine, your engine won't be this clean at those miles. It won't even BE.

 

[Astro14]

Most likely. Seen that on a few engines before. And to those that suggest 10,000 mile oil changes with synthetic are perfectly fine, your engine won't be this clean at those miles. It won't even BE.

Yeah, right. You just make stuff up for the sake of argument? A proper synthetic keeps the engine just as clean, and a proper interval based on the synthetic performance specification will result in an engine that is just as clean.

Here is an engine run on 10,000 mile intervals - and only 10,000 mile intervals

Under the valve covers, 2005 Mercedes SL600

While changing the sparkplugs on my wife’s roadster, I discovered a minor valve cover leak. Mercedes books about 8 hours* for a sparkplug change on the car, which has the M275 V-12 engine with 2 plugs per cylinder. Yes, that’s a total of 24 iridium plugs. since the coils have to come out to get...

bobistheoilguy.com

Here are a couple of engines with even greater intervals -

Under valve cover pictures - 2014 Dodge Durango 164,000 miles total, 52,000 miles on HPL HDEO 5w-20

Most recent UOA: https://bobistheoilguy.com/forums/threads/dodge-durango-3-6l-hpl-ck-4-5w-20-18-700-miles-on-oil-158-700-total.370335/ These pictures are taken with a bore scope through the filler in the driver's side valve cover. I started using HPL HDEO 5w-20 in this vehicle at 112,000...

bobistheoilguy.com

Under valve cover pictures - 2016 Dodge Charger 70,000 miles total, 15,000 miles/33 months on HPL HDEO 5w-30

Most recent UOA: https://bobistheoilguy.com/forums/threads/2016-dodge-charger-3-6l-66-000-total-miles-11-000-miles-on-hpl-5w-30-hdeo-cj-4.366962/ I bought a bore scope so I could get some pictures under the valve cover of the Charger 3.6L with 70,000 miles on the clock. The oil is HPL CJ-4...

bobistheoilguy.com

You can’t make blanket generalizations like that. Besides, you bought 50 jugs of Mobil 1, so, you’re clearly a synthetic fan, right?

Post in thread 'Trying to liquidate my excess oil this year.'
https://bobistheoilguy.com/forums/t...e-my-excess-oil-this-year.353273/post-6078496

 

[atikovi]

Yeah, right. You just make stuff up for the sake of argument? A proper synthetic keeps the engine just as clean, and a proper interval based on the synthetic performance specification will result in an engine that is just as clean.

Here is an engine run on 10,000 mile intervals - and only 10,000 mile intervals

Under the valve covers, 2005 Mercedes SL600

While changing the sparkplugs on my wife’s roadster, I discovered a minor valve cover leak. Mercedes books about 8 hours* for a sparkplug change on the car, which has the M275 V-12 engine with 2 plugs per cylinder. Yes, that’s a total of 24 iridium plugs. since the coils have to come out to get...

bobistheoilguy.com

Here are a couple of engines with even greater intervals -

Under valve cover pictures - 2014 Dodge Durango 164,000 miles total, 52,000 miles on HPL HDEO 5w-20

Most recent UOA: https://bobistheoilguy.com/forums/threads/dodge-durango-3-6l-hpl-ck-4-5w-20-18-700-miles-on-oil-158-700-total.370335/ These pictures are taken with a bore scope through the filler in the driver's side valve cover. I started using HPL HDEO 5w-20 in this vehicle at 112,000...

bobistheoilguy.com

Under valve cover pictures - 2016 Dodge Charger 70,000 miles total, 15,000 miles/33 months on HPL HDEO 5w-30

Most recent UOA: https://bobistheoilguy.com/forums/threads/2016-dodge-charger-3-6l-66-000-total-miles-11-000-miles-on-hpl-5w-30-hdeo-cj-4.366962/ I bought a bore scope so I could get some pictures under the valve cover of the Charger 3.6L with 70,000 miles on the clock. The oil is HPL CJ-4...

bobistheoilguy.com

You can’t make blanket generalizations like that. Besides, you bought 50 jugs of Mobil 1, so, you’re clearly a synthetic fan, right?

Post in thread 'Trying to liquidate my excess oil this year.'
https://bobistheoilguy.com/forums/t...e-my-excess-oil-this-year.353273/post-6078496

Great examples there. 52,000 miles, 164,000 miles, 70,000 miles. Let me know how they look at nearly 400,000 miles like the OP.

 

[Kira]

In the OP's photos I cannot see what powers the cam shafts.
Where's the sprockets?

 

[Astro14]

Great examples there. 52,000 miles, 164,000 miles, 70,000 miles. Let me know how they look at nearly 400,000 miles like the OP.

Those engines are spotless, and you know it. They’re not going to suddenly die, or sludge up, when the regimen is clearly working.

I will chalk this up as another one of your troll statements,

Most likely. Seen that on a few engines before. And to those that suggest 10,000 mile oil changes with synthetic are perfectly fine, your engine won't be this clean at those miles. It won't even BE.

 

[dnewton3]

This is a function of several criteria and characteristics coming together at the same time and place.
THERE IS NO ONE SIZE FITS ALL ANSWER TO THE TOPIC OF ENGINE CLEANLINESS.
What we have here is a great anecdotal example of a system that worked well. The oils used, the OCIs, the specific engine in this example, etc; they all worked in concert to achieve this result. That does not mean that other combinations won't do as well, or would do worse. There are generalities that can be made at the extreme ends of "that's not a good idea", but there is no "OSFA" answer.


As to why the one head may have a bit more varnish, I have a potential idea as to why. It's possible that the head with slight varnish may not have quite as good coolant flow, or the coolant flow in that head is secondary to the other head. That would make for ever so slightly higher head temps in the suspect head, and therefore may be (not assured, but perhaps) be right on the cusp of varnish development. I do not know the intricacies of the coolant system on the engine in question here, so I cannot say with certainty. I'm only offering a possible cause; that the varnished head runs a tad hotter than the cleaner one, for some reason. I know that some engines cool the heads concurrently, whereas others cool the heads sequentially. That might be a potential explanation. Regardless, after nearly 400k miles, it's not enough to worry about; the varnish is very light and not a cause for concern.

 

[SC Maintenance]

This is a function of several criteria and characteristics coming together at the same time and place.
THERE IS NO ONE SIZE FITS ALL ANSWER TO THE TOPIC OF ENGINE CLEANLINESS.
What we have here is a great anecdotal example of a system that worked well. The oils used, the OCIs, the specific engine in this example, etc; they all worked in concert to achieve this result. That does not mean that other combinations won't do as well, or would do worse. There are generalities that can be made at the extreme ends of "that's not a good idea", but there is no "OSFA" answer.


As to why the one head may have a bit more varnish, I have a potential idea as to why. It's possible that the head with slight varnish may not have quite as good coolant flow, or the coolant flow in that head is secondary to the other head. That would make for ever so slightly higher head temps in the suspect head, and therefore may be (not assured, but perhaps) be right on the cusp of varnish development. I do not know the intricacies of the coolant system on the engine in question here, so I cannot say with certainty. I'm only offering a possible cause; that the varnished head runs a tad hotter than the cleaner one, for some reason. I know that some engines cool the heads concurrently, whereas others cool the heads sequentially. That might be a potential explanation. Regardless, after nearly 400k miles, it's not enough to worry about; the varnish is very light and not a cause for concern.

Hmmm. You might be on to something with the cooling loop. I’ll look at the manual when I get a chance.