If it's like the colour plating out like Royal Purple, it's probably not a big deal, but if it's a light layer of varnish, well, my observations apply.
This is why quality engine flushes should be used at every OCI if there is any sign of varnish. Also, unless oil changes are meticulous engine flush should be used every OCI as is the practice in most Aussie workshops.
Why not just use a quality engine oil that has the correct components & composition to prevent varnish in the first place? Solvents in most engine flushes are not lubricants, and should not be used while the engine is being driven. The correct oil will both clean deposits and keep insolubles & particulates in suspension so they can be captured by the filter.
+1. There are several oils that are known to have the appropriate formulation to maintain and to clean an engine. Most oils will not clean a varnished or dirty engine as they are not properly formulated to do that sort of cleaning.
It could take a year or more going on 6 month OCI. A quality flush does the job straight away and won't harm the engine and you can use a suitable oil to keep the engine cleaner at the oil change.
No, that's why you use an ester or AN-based product to slowly dissolve it; bring it back into suspension and removing it from the engine. This way, you don't risk liberating large chunks that could plug pickup screens for example.
A flush will not clean-up all existing deposits, and you certainly risk, if it's an aggressive solvent:
Dispersants aren't breaking up large chunks that are aggressively liberated and if they aren't being aggressively liberated, then what are you gaining over the slow, measured approach, using something with AN's or esters in it that will slowly dissolve the material and put it in suspension, allowing the filter to capture it?
Overkill is offering good advice. It's definitely worth considering.
We are talking about varnish, not sludged up engines. I'm happy to use the cleaning oil, just give it a good start.
Please go back to my post where I described deposit types, in detail. There are various grades/levels of varnish. Once you've gone over that, we can resume this discussion.
I'm talking about using engine flush in any engine unless its grossly neglected. I do not see why you wouldn't. There is really no reason to not use them unless you are relying on old wives tails and/or older products from long ago like ATF and diesel flushes etc.
I'd like for you to explain to me what you feel would describe a situation where you'd intentionally use a flush rather than just using a high quality oil. You seem to feel these are somehow required, which has me curious, as I've had many an engine apart that have been run on quality oils and I can tell you, a flush wouldn't have made them any cleaner and it certainly wouldn't have benefited the engine. In fact I'd argue that by introducing the flush, I could have negatively impacted the tribofilms and established anti-wear chemistry that the quality lubricant had already laid down while keeping the engine clean.
If the car has been maintained perfectly from its 1st service and using quality oil, a flush may not be needed. Now I understand that is the majority of people on this forum. However, a less well maintained car will suffer from things such as varnish/sludge etc especially when using less than top tier oils or various oils over extended OCI etc.
Excellent post. Regarding varnish and sludge, imo pushing any oil to it's limits to get the most life out of it can often lead to sludge and varnish. I'd rather use a good quality oil, and not push it to the fullest extent of its useful life. I'd rather change it early, waste money in the minds of some, but sleep easy knowing I'm giving my engine a better shot at staying clean. While an extended drain oil is designed for just that, extended drain intervals, contaminants held in suspension longer don't always get filtered out. They circulate longer, and can add to wear, and possibly sludge and varnish as they circulate and are subjected to more cold/hot cycles. In order for them to be removed the oil needs to be drained. Old school thinking perhaps but........... Opinions will vary.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.
You keep mentioning “quality oil flushes”… can you point me to the ASTM, API, ACEA, SAE, or international standards organization that regulates & ensures proper engine oil flush formulations? How is one supposed to know without a shadow of a doubt that their flush choice is a quality engine flush? Simply claiming that a flush “did no harm” is not evidence of a benefit.
Thanks for the comedy, I'm just talking about an engine flush product that isn't ATF and/or one of the fine backyard concoctions that members come up with here.
