Using modern synthetic oils rated for your vehicle , using a good oil filter , regularly checking PCV valve for proper operation and OCI's of less than 5K miles or 12 months max - this is all I can think of to reduce the likelihood of sludge & varnish ... Your thoughts and experiences ?
Reducing Likelihood of Sludge & Varnish ?
- Thread starter ChrisD46
- Start date
Air filter and vacuum leaks.
PAO and Ester
Sludge is one thing, while varnish is another.
Just because you have the latter, does not mean you'll experiece the former.
Lately I've seen way too many examples of 5k OCI vehicles here, while on top shelf synthetics, yet still with heavy varnish on valvetrain. And if there is varnish in easy to see areas, then there is likely even bigger issues in areas you can't see. Like piston rings for example. So I kinda found myself really rethinking the 5000 OCI... But then again there is that 1.4T Cruze with extended OCIs while tuned, and it looks spotless with AMSOIL. So are AMSOIL and HPL the only ways to have a clean engine and prevent stuck rings issue down the road? Or is it widely available synthetics, but at shorter intervals?
I understand that some folks have shown some rather ugly examples. One particular example looked horrible on M1 0W-40. I'm calling that one out as NOT TRUE. I've seen thousands of engines, not a single regular M1 user had similar varnish. Not one. In fact, regular M1 users never have sludge, varnish, clogged piston drain holes or coked turbochargers.
What I have seen is people using 0W oils and changing at 12,000+ mile intervals and experiencing cam lobe, roller follower and timing chain wear. This should come as no surprise.
dnewton3
Staff member
This topic is waaaaaayyyyy to complex and varies across all manner of criteria to have a one-size-fits-all answer.
- First of all, sludge and varnish are different. Sludge is accumulation of combustion byproducts and oxidation of the lube, obviously not good, and needs to be avoided. OTOH, varnish is harmless discoloration of surfaces; nothing to worry about.
- Next, the engine design lends itself to being either clean running, or having a proclivity to sludge. As discussed in another recent thread, there are things that make for good or bad conditions (see that thread).
- Then, the lube chosen is a factor; what kind of base stock? What cleaning agents? What capacity for holding contamiation in suspension? Etc
- Finally, the OCI duration, relative to the factors above.
There are engines that have exhibited a propensity to sludge up even using synthetic lubes and 5k miles OCIs.
There are engines that have shown to be very clean running even when pushed out to 15k miles with conventional lubes.
There are examples of lubes that have good wear traits, but leave much contamination behind.
There are examples of lubes that not only run clean, but scrub off years of previous contamination loading.
You want a specific answer, you have to ask a specific, detailed question covering all known parameters and products and conditions.
You raise a generic question, you deserve a "Well ... it depends ..." answer.
The factors you mention may or may not be enough to ward off sludge.
10k miles or once a year has left me sludge free using Warren brand synthetics ( SUPERTECH AND kIRKLAND)
Because I have a GDI engine and do a lot of big city , suburban driving , I do not exceed 4K miles OCI and usually change at the severe service 3,750 mark (by then the soot level is up there making the oil look pretty bad in a GDI engine) .
Your oil choice to address this quote : "There are examples of lubes that not only run clean, but scrub off years of previous contamination loading" ?
My Sportwagen is spotless (pics in several posts here) and that was with primarily Liquimoly oils/additives which gets beat up here most of the time. I don't think you can correlate this issue at all without a ton of data including the engine, the oil, the use, etc. So much can differ. 5K on any modern oil should be more than ok.
You use LM engine flush on every oil change, correct? And strictly by instructions, or go past the 15 min idle limit?
No, but I've used on quite a few (not every time). I go 10-15 min max which is following the directions. I really think this helps every few changes but its gets poo poo'd here and I'm a pariah b/c of it ahahah but many of the same folks then go on an on about cleaning etc. with all these different methods where this is simple and apparently effective and keeping things tidy. A can was $10 from FCP Euro but has gone up per inflation ~$5 so $15 now. Certainly not breaking the bank to use it sometimes and there is no adverse issues that I can find/no reason for there to me. Maybe a once/year thing is a reasonable way to do it.
I just checked my records - I've used the LM Engine Flush 6x over the 90K miles/4.5 years I've had it. I'm due for it next oil change.
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Avoid very short trips.
And changing your oil and filter, using an approved product at 1/2 of the OEM interval usually works.
(Obviously, if you’re using a boutique product or have unusual operating conditions, this bit of blanket advice may be even less relevant.)
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