So what about a little varnish?

JHZR2

Staff member
Messages
46,293
Location
New Jersey
first off, I believe in and use synthetic oils heavily. That said, often people talk about removing a valve cover and seeing varnish when using dino oils in their engines. I say so what? If a dino oil repeatedly gives excellent results in your engine, does a thin layer of varnish on surfaces do anything or is it any sort of an issue? I can see if you have a lot of sludge in your oil pan; this means that the oil is breaking down, and the junk is potentially circulating and not protecting well. But varnish? Id guess thats just from the lighter oil components flashing off and then condensing/solidifying on cooler surfaces. So what? My mother's 97 plymouth breeze had dino done at the dealer for the first 40k of its life. Since then, Ive been doing the changes with Mobil 1. She drives 5 blocks 4 times a day, and maybe once a day does the temp needle in the car go up all the way. Her analysis results are still excellent, Ive posted them in the UOA forum. However, when I pulled the valve cover, just yesterday, there is still varnish on the inside surface of the valve cover (nothing else has varnish on it though). Maybe its lefotver from dino oil use. Maybe its from the M1. Does this make any difference? I dont think so. Does it make any difference if the varnish was nearer to other 'working' parts? Dont think so either. Would varnish form on working and moving parts? I doubt it. So as long as a dino oil doesnt sludge up, and so long as it is protecting reliably, does the formation of varnish on non working surfaces really matter? Im not trying to put down synthetic or raise up dino, nor am I trying to make up a dino vs synthetic argument. I just have heard a lot about varnish spots when engines are opened up, and saw them on my mother's valve cover after 30k on m1. So Im just curious. Thanks, JMH
 
Messages
2,569
Location
College Dorm...
Two things pop into my mind... 1. Varnish and deposits from mineral PCMO's "covering up" seals causing them to no longer function properly. 2. The piston ring area. Mineral PCMO's break down in this area (to a greater extent than HDEO's and synthetics) and that leads to all sorts of issues/problems.
 

tpi

Messages
200
Location
So. CA
I've bought used cars with varnish under the valve cover, heck even black mayo sludge because the price was right. Even the el sludgo ran for an additional 80K miles (I didn't try to disturb the deposits, but initiated regular oil changes). On cars I buy new I try to maintain them so no varnish forms, just a thing I have about it.
 

JHZR2

Staff member
Thread starter
Messages
46,293
Location
New Jersey
ok, thanks for the replies. So, now I gues the question is, is varnish formation a factor of a dino oil being a dino oil, or is it more due to change intervals or oil quality. i.e., can you run dino, change it regularly, and have no varnish? Similarly, can running synthetic oil still result in some varnish formation? Thanks very much, JMH
 
Messages
656
Location
Massachusetts
As the old saying goes: "Varnish happens". Nearly all oil will eventually leave a slight discoloration, but some worse than others. It may be the case with your mom's car that the dino left the varnish and the M1 never cleaned it up. But the M1 probably didn't add to the problem either. A little varnish or discoloration in the engine is nothing to worry about. Thick black crusty sludge is another issue all together.
 
Messages
2,768
Location
Tn
I believe that Molekule has written on the differences between varnish and lacquer and what causes this in the "Question of the Day" forum. Looking at slight color variation beneath an oil cap or something can be deceptive. Even a top notch syn that may clean and lube very well, may still need to be changed if the filter system doesn't keep the solids in check. Discoloration does not mean there is heavy or significant varnish or lacquer buildup.
 
Messages
562
Location
Austin, TX
Varnish on the heads can plug up the oil return holes. The bigger problem is piston ring deposits, which can lead to compression loss and oil burning.
 
Messages
2,768
Location
Tn
quote:
Originally posted by JHZR2: ok, thanks for the replies. So, now I gues the question is, is varnish formation a factor of a dino oil being a dino oil, or is it more due to change intervals or oil quality. i.e., can you run dino, change it regularly, and have no varnish? Similarly, can running synthetic oil still result in some varnish formation? Thanks very much, JMH
If synthetics were perfect, then, there would be no need for products like LC and FP. Even premium synthetics much be changed because of insolubles and you will still get some deposits, especially in a turbo.
 
Messages
302
Location
Chicago
Many people, including myself, have run nothing but a steady diet of synthetic since new, and still have varnish. (And by "synthetic," I guess I mean "Mobil 1.") I think a lot of it also has to do with the specific application -- average head temperatures and the like for that specific vehicle/engine.
 
Messages
2,768
Location
Tn
quote:
Originally posted by Geoff: The bigger problem is piston ring deposits, which can lead to compression loss and oil burning.
That would be one of my main concerns and the need to do good maintenance. [Big Grin] Very important point. [Cheers!]
 

tpi

Messages
200
Location
So. CA
quote:
Originally posted by kev99sl: Many people, including myself, have run nothing but a steady diet of synthetic since new, and still have varnish. (And by "synthetic," I guess I mean "Mobil 1.") I think a lot of it also has to do with the specific application -- average head temperatures and the like for that specific vehicle/engine.
Interesting. In so. CA I haven't seen any varnish in engines I bought new which had Mobil 1 and 6-10,000 mile OCI. These range from Chevrolet small block, Ford Modular, Toyota 4 cyl. all with 100-150,000 miles of mostly hwy driving. I bought a used jeep w/ 100K miles which had reliable 3000 mile OCI using dino and had very little varnish deposit under valve cover. This also saw extensive hwy driving. I recently looked in the valve cover of my 99 PSD using Delo 400 at 5-10,000 OCI and it is perfectly clean @ 97,000 miles. I agree with the previous posts re: piston ring function, and oil seal function relating to sludge and varnish. Most of the premature leakers had excessive deposits in the engine.
 
Top