Varnish: What's the downside?

[Shel_B]

After reading a couple of threads that showed "under the valve cover" pictures, I came away knowing that quite a few folks here feel that varnish is not an issue, isn't a problem. I wonder about that. Is there a downside to varnish? How might it be detrimental to an engine? Thanks!

 

[RooflessVW]

Varnish under the valve cover could be indicative of worse elsewhere, like the piston rings.

 

[MRC01]

Upside: may protect coated surfaces from corrosion.
Downside: may contribute to sludge, impairing seals, orifices, etc.

 

[DemoFly]

Varnish under a valve cover is not a smoking gun in most engine designs. The PCV is usually on the valve cover.

Varnish is always bad. It's oil in the process of turning into sludge. I know of the valve cover thread you speak of, and most of the people in that thread are incorrectly calling discoloration, "varnish".

 

[Soft Cars]

It's a hot button issue. I have nothing personal against people who are pro-varnish. It's their car and their choice.

 

[CarbonSteel]

It's a foundation for continued varnish deposits to form which will more than likely turn to sludge given enough time.

 

[Dave9]

Your post is kind of strange. Varnish, it happens, but the issue is whether sludge builds up, if it's only the start of a problem or kept in check by regular oil changes.

This kind of vague, curiousity post without any specific vehicle problems, borders on paranoia if you are just doing the regular OCI you're supposed to.

If you are instead hoping to keep a vehicle running forever, that isn't going to happen. Something will take its toll.

Keep in mind that people observe varnish on non-wear areas. On a wear area, it isn't an issue, rather the concern is blocking oil passageways, where the flow of regularly replaced, good quality oil does its purpose.

 

[dishdude]

Personally I would not be concerned with varnish. For example, I would do nothing but regular ocis on this engine.

1993 Dodge Shadow - under the valve covers

Hey guys, doing the valve cover gaskets on my recently acquired 93 Shadow. 62,000 miles. All I can say is.... varnishpalooza. According to the thick pile of service records, it's had a steady diet of conventional and semi-syn. At this point, I'm grateful there's no sludge.

bobistheoilguy.com

 

[92saturnsl2]

When I think of varnish, I think dark colored baked on oil, discoloring the base metal. That's usually heat and mileage related, not necessarily lack of maintenance. It's never caused me any problems, and I've seen at least some amount of it on any high mileage engine I've had. Some vehicles this issue occurs primarily on the side of the engine (in a V config) where the PCV valve is located. Again, not really an issue, IMO.

Deposits and sludge are a different animal. Deposits are caked on carbon or other such coating that can be literally scraped off. That's probably a bad thing as it can dislodge or contaminate new oil over time. Sludge is the worst offender, which is either bad engine design or lack of maintenance, usually a combination of the two.

So no, I've never seen any downsides to an engine having varnish and consider it normal especially on higher mileage engines.

 

[Jetronic]

After reading a couple of threads that showed "under the valve cover" pictures, I came away knowing that quite a few folks here feel that varnish is not an issue, isn't a problem. I wonder about that. Is there a downside to varnish? How might it be detrimental to an engine? Thanks!

It can also make actuators stick, think vvti here, or can reduce cooling (think turbo). And it's definitely a precursor to much worse, like stuck rings.

 

[adams355]

Its not good for fresh oil

 

[Trav]

After reading a couple of threads that showed "under the valve cover" pictures, I came away knowing that quite a few folks here feel that varnish is not an issue, isn't a problem. I wonder about that. Is there a downside to varnish? How might it be detrimental to an engine? Thanks!

Varnish is something to be concerned about, in old engines it caused sticking lifters and sticking rings and when bad enough the engine became a smoking noisy pile. In modern engines there are many systems that rely on solenoids to activate cam systems like vtec, avcs, vcm, ivtec, vtc, spool valves, etc in addition to hydraulic chain tensioners, turbo systems, etc.
When these get badly varnished it can cause the engine to almost or even completely stop running and cost big $$ to repair. All these systems require clean oil to operate properly. It is much easier to prevent than repair, change the oil.

 

[Shel_B]

Thanks for the responses. There seem to be more things than I gave thought to about the downside of varnish. It's definitely something I'd like to avoid.

 

[Soft Cars]

Rumor has it that RedLine oil is extremely aggressive at removing varnish. After two OCIs the metal is back to raw silver again.

 

[SubieRubyRoo]

Varnish is an insulator. Valve springs (especially highly stressed ones) are easily compromised by excessive heat.

 

[SubieRubyRoo]

Rumor has it that RedLine oil is extremely aggressive at removing varnish. After two OCIs the metal is back to raw silver again.

Instead of rumors, are there any pics that prove this? Those would be more helpful than conjecture, plus be fun to look at.

 

[OVERKILL]

Copying my post from @Graham Piccinini's thread:

I've posted on this subject many times and often get dismissive comments with respect to my position on varnish.

The reality is, as @wwillson alluded to with respect to the carbonaceous material in the ring lands, if you have varnish where you CAN see, you have a lot worse where you CAN'T.

That is, if the head(s) and valvetrain have managed to accumulate deposits, this means that the additive package of the oil has been overwhelmed. The dispersants and detergents are no longer able to do their job and so the materials they are tasked with holding in suspension through the mitigation of agglomeration and prevention of laying down, hit a saturation point and they plate-out. This is varnish.

Now, if you think it's bad seeing this showing up in these areas of moderate heat and reasonable flow, it's significantly worse in the ring pack where flow is extremely low and the conditions are the harshest.

Now, @aquariuscsm said that varnish is the precursor to sludge. That's only partially correct. Sludge and varnish are comprised of most of the same materials, but varnish doesn't necessarily lead to sludge and sludge doesn't typically lead to varnish. But you can have both happening in the same engine.

I've posted this chart before:

You can see that resins plating out leads to varnish. Varnish + carbon, water and solids can lead to sludge. But so can just those resins + carbon, water and solids. Varnish requires heat, sludge does not. If you have heat, you probably don't have water, which is why you end up with varnish instead of sludge.

These resins + soot can form silty deposits (often improperly referred to as sludge), or, they can form a thick dark varnish (heavy varnish) called lacquer.

It's easy to figure out what gets deposited in the ring land area, based on this data.

When liberated, it looks like this in your oil filter:

@wwillson has more examples.

 

[Jetronic]

Instead of rumors, are there any pics that prove this? Those would be more helpful than conjecture, plus be fun to look at.

Esters in general are good at removing deposits. Redline has a very healthy dose of it in there performance series.

The engine in my new car had a lot of varnish, I added some ester containing oil and it stopped excessive consumption + started cleaning the varnish in as little as 3000 km.

 

[BMWTurboDzl]

Copying my post from @Graham Piccinini's thread:

I've posted on this subject many times and often get dismissive comments with respect to my position on varnish.

The reality is, as @wwillson alluded to with respect to the carbonaceous material in the ring lands, if you have varnish where you CAN see, you have a lot worse where you CAN'T.

That is, if the head(s) and valvetrain have managed to accumulate deposits, this means that the additive package of the oil has been overwhelmed. The dispersants and detergents are no longer able to do their job and so the materials they are tasked with holding in suspension through the mitigation of agglomeration and prevention of laying down, hit a saturation point and they plate-out. This is varnish.

Now, if you think it's bad seeing this showing up in these areas of moderate heat and reasonable flow, it's significantly worse in the ring pack where flow is extremely low and the conditions are the harshest.

Now, @aquariuscsm said that varnish is the precursor to sludge. That's only partially correct. Sludge and varnish are comprised of most of the same materials, but varnish doesn't necessarily lead to sludge and sludge doesn't typically lead to varnish. But you can have both happening in the same engine.

I've posted this chart before:

You can see that resins plating out leads to varnish. Varnish + carbon, water and solids can lead to sludge. But so can just those resins + carbon, water and solids. Varnish requires heat, sludge does not. If you have heat, you probably don't have water, which is why you end up with varnish instead of sludge.

These resins + soot can form silty deposits (often improperly referred to as sludge), or, they can form a thick dark varnish (heavy varnish) called lacquer.

It's easy to figure out what gets deposited in the ring land area, based on this data.

When liberated, it looks like this in your oil filter:

@wwilson has more examples.

Where does staining fall into this?

 

[Jetronic]

Where does staining fall into this?

Most likely just a very thin varnish layer.