Conventional oils and varnish

[passgas55]

What damage is done to an engine if you use conventional oil and you get some varnish in your engine? I posted a while back on another forum
that I have no problem doing 10k mils oil changes running Chevron Supreme 10/30 in a 2007 4.3v6 chevy. Seems like I was going to kill my engine because
I will have varnish in my engine. If the engine sludged up I can see the problem but some varnish so what?

 

[dogememe]

Start using the 5w30 flavor of Chevron Supreme and it's a synthetic blend

but who cares! While I'm a fan of synthetics it's true that many vehicles live a long and happy life on conventional oils.

 

[JC1]

I had Varnish in my 1998 Sienna. Bits of small sludge too, but nothing major. I don't think it will be any issue in that motor.

 

[UNC063]

Thats really depends on engine type. But 10k on conventional oil is pretty long oci according to me.

 

[StevieC]

Varnish won't hurt anything.

 

[demarpaint]

My 2000 Century was a mess with about 80K miles and very well maintained using conventional oil. I'd agree it depends on the engine type. For the cost of synthetic oil with rebates etc, "I' see no point in using conventional oil.

 

[JC1]

Originally Posted by JC1
I had Varnish in my 1998 Sienna. Bits of small sludge too, but nothing major. I don't think it will be any issue in that motor.



Oh forgot to comment about the 10K on conventional. That is a long drain interval. How long would it take you to get to 10K? Unless you are doing 5K of driving a month, I wouldn't run it that long (unless you are trying to kill that motor or don't care about it).

I would probably go 6K max.

 

[LeakySeals]

Depends on the design of engine. In some engines Like a GM v8 varnish is harmless and washes away with a synthetic oil like Mobil 1. But there are some engines with tiny oil passages like (for example) Toyota I4 that never recover without rebuild or repair. The varnish clogs up the piston oil return holes. Flow is reduced until its stopped. Once the flow stops, the oil in the tiny holes overheats, flashes, hardening to a solid mass of carbon. With no escape, oil builds up on the pistons and is consumed. Fouling the rings. Getting them stuck. And the engine is stuck burning 1qt of oil every 1-2k miles forever or until the engine is torn apart and the piston oil return holes cleared. Or the tiny holes feeding the VVT actuator gets clogged, and there is not enough hydraulic oil pressure unlock the actuator at startup. You get that horrible startup rattle that eventually requires actuator replacement. Not cheap. So no, varnish is not always harmless. Get rid of it ASAP.

 

[Zee09]

I like CS oil myself.
But honestly you can buy fs oil for $3 more.
And the 5w30 advice was good but Chevron cranked the price of that weight to fs pricing .
Plenty of great fs oils at $17-$18 a jug.
For your 10k runs move over to fs.

 

[StevieC]

Just thought I would add some pictures just in case it's not really clear.

This is what Engine Varnish looks like which isn't a problem:

This is what Engine Sludge looks like which IS a problem because it can plug up the sump pick-up tube screen, piston ring oil return holes, oil galleries/passages, VVT solenoids holes / cam phasers etc. and starve the engine for oil because it can't flow properly or get at critical engine parts to dissipate heat.

 

[CT8]

Originally Posted by StevieC
Varnish won't hurt anything.

+1.

 

[Zee09]

Yeah but that sludge will never let the engine rust...…………..

 

[StevieC]

Originally Posted by Zee09
Yeah but that sludge will never let the engine rust...…………..

And you will have a large supply of what resembles wheel bearing grease too.

 

[tig1]

Originally Posted by StevieC
Varnish won't hurt anything.

Don't believe varnish is harmless. Varnish is caused by the oil oxidizing (thickening), as the oil is reacting to heat in an unfavorable way. This can also lead to ring coking with causes blow by. Use a quality synthetic oil and this won't happen.at 10K OCIs. I know. That's been my OCI for 41 years with Mobil 1 oils.

 

[Trav]

Originally Posted by StevieC
Varnish won't hurt anything.


That depends on the engine and the amount of varnish. You cant make a blanket statement like that, if the engine has hydraulic timing chain tensioner(s), VVT, VCM, etc varnish can be a very real problem. Honda spool valves for example are known to stick with very little varnish in them.
Varnish can also cause hydraulic lifters/lash adjusters and piston rings to stick. It also acts as a primer of sorts for harder deposits and sludge, not exactly the harmless stain many have claimed it to be.

The BMW picture you used from another thread is not much more than just a stain but it doesn't have to get much worse like Clinebargers job in the second picture to cause issues.
This engine had both, heavy varnish on the rear bank that caused the spool valve to stick and heavy deposits on the front bank.

 

[StevieC]

Originally Posted by tig1
Originally Posted by StevieC
Varnish won't hurt anything.

Don't believe varnish is harmless. Varnish is caused by the oil oxidizing (thickening), as the oil is reacting to heat in an unfavorable way. This can also lead to ring coking with causes blow by. Use a quality synthetic oil and this won't happen.at 10K OCIs. I know. That's been my OCI for 41 years with Mobil 1 oils.

Of all the Euro engines we have repaired they have all had varnish in them (IMO from much longer drain intervals), but none of them suffered because of it. Are there one off cases that could be sensitive to varnish sure, but it's not common place.

 

[Trav]

This is after cleaning, notice the spool valve before cleaning, that's all the varnish it took for make it stick and the engine to run on 3 cylinders instead of 6.

 

[StevieC]

Trav, that amount of varnish in the first picture you posted (heavy brown varnish) isn't normal varnish that is from OCI's being pushed too far too many times or using an oil not capable of the OCI. The varnish picture I posted is normal varnish accumulation as seen in some engines. Really common in Euro engines that I've had the joy of taking apart where regular maintenance is performed. (We performed it on time all the time) and still there was some varnish. Vehicle operated fine other than needing valve cover gaskets.

I did mention in my reply to Tig that some engines are sensitive to varnish but it's not the norm and certainly not at the levels shown in the picture I provided.

 

[Trav]

That is on a 5K synthetic OCI. People here went nuts when I first posted this issue with some Honda engines almost 10 years ago then a few years later more and more started showing up.
Toyota 3.0 had bad problems, so bad in fact Toyota had a TSB requiring 3K OCI with synthetic oil. Just because you don't see the varnish on the top end it doesn't mean the piston rings are not getting sticky so you cant make that statement either unless you are doing a compression test on every engine.

I did a low mile R32 with a spotless top end, it ran well but has universally lower compression than spec, an overnight piston soak brought it right back to spec and it stayed there with a shortened OCI.

 

[Onetor]

If is the key word.