Just an experience question:

How likely is a sludge problem inside of a Slant-Six, and is there a preferred method of managing it, aside from removing the oil pan?

My engine has 38,000 miles, and has done a lot of sitting over the past 30 years.
HOWEVER, when I pulled the valve cover, everything was shockingly clean. I mean, really nice.

I have in the past had cars with real sludge issues. A '71 Skylark with a 350, for example, which, when I pulled the valve covers, yielded perfect casts of the insides of the valve covers, with tiny little open areas around the valve springs and rockers. (Drove that car cross-country without a problem, sludge and all).

This engine looks much better than THAT, and I wouldn't think much of it, if it weren't for some folks I've read describing ungodly amounts of sludge in their oil pans.

So, for those of you who've taken apart a dozen Slant-Sixes, is it advisable for me to do anything special?
Sludge-dissolving additive?
NO sludge-dissolving additive, for the love of God!?
Get crazy with the oil filters? (2-qt filter, "Super-Duper" "XP" filter, etc.?
Anything else?

I wasn't going to do anything at all, but a few mentions here and there got me a little spooked.

Thanks,

– Eric

Drain the oil. See what it looks like. Replace the oil filter. Drive the car.

Yeah. Dun that.

Was what I'd been planning to do.

Car was well maintained during the years the little old lady was using it.

Thanks.

The most recent one I had was a 64 engine, I had bought it with it's trans just for a couple of pieces and passed it on.
While I had it I fired it up while sitting on my trailer, just for a minute or so. (I only dribbled a little gas in the carb, didn't hook up a line to the fuel pump)
This engine has the cartridge style oil filter (not the more common screw on one we all know)
While I had it I had a request for the oil pan, it was a weird one as id never seen a /6 with a front sump. I traded pans with the guy that wanted mine, and installed the pan he sent me just to keep it sealed up.
When I drained the oil it was black as tar, and the consistency of gas. I then pulled the pan with the engine on a stand, and glad that I never rolled the engine over on the stand once I saw the inside of the pan..... Wish I had a picture.
It had a heavy layer of sludge in the sump, it was definitely deeper than the pickup.
This sludge was mouse gray and the consistency of mayonnaise.
When I ran it, the only thing goofy I noticed was that super thin oil seeping out the crimped seam on the oil sending unit. With solid lifters, I didn't hear any noise that would show distress from low oil pressure. Had it had hydraulic lifters I suspect that I probably would have.
Absolutely none of the sludge came out of the drain plug when I had that out. Had it been in the truck still and I was going to be driving it, I would have just poured oil in , drove away and probably not known about that nasty mess until rods started knocking.
After I had that pan off I then rolled the engine on the stand to put the other pan on, and surprisingly it was pretty clean up into the block. No sludge globs hanging off the inside of the crankcase. I never did pull the valve cover while I had that engine here.
Having seen what I had seen made me glad I pulled that pan as I believe my buddy who ended up with that engine, intended on dropping it right into his car as is and driving it.

Thanks, Greg.

Sounds like that motor had gotten some water in it in the past, whether from condensation or some "unforeseen circumstance." That's usually what makes grey or brown sludgy stuff, in my experience.

This engine is definitely not that one, so I'm not worried, but... Damn.

Would have been interesting to run it like that to see how long it would take to break. If it ever did.

I appreciate the reply!

- Eric

Unlikely to very likely, depending on how it's been run, what oils have been used, how often they've been changed, how long it's sat, and other variables.
That's a good sign.
Good job their oil pans aren't on your engine, then.

Use thoughtfully-chosen oil (a reputable brand of 10w30; no benefit from expensive boutique brands and no need for additives of any kind) and a thoughtfully-chosen filter. It will also be a good idea to service the oil pressure relief valve to make sure it's doing its job, as described in these two threads: thread 1, thread 2.
Is correct; they are far more apt to cause harm than do good. There are techniques for cleaning out an engine that needs it and can't, for whatever reason, be taken apart and cleaned properly, but this is not a preventive/on-speculation deal.
2-quart filter is a pointless nuisance unless you gotta-just-gotta have bragging rights vindicated by flipping open the hood and proudly pointing to your extra-extra-tall oil filter.

You can spend a great deal of money on oil filters, if doing so will give you a warm fuzzy. You can change the oil at wastefully-short intervals (3,000 miles, for example), if abject squander of money and oil makes your socks roll up and down. But really, there is no need of this. The Slant-6 lived to unusually old age even with the relatively pathetic oils and filters of their day. You do have to be watchful of poor-quality filters, but you don't have to obsess about it. The best ultrapremium filter is likely still the Fleetguard LF3487. Used to be able to find them surprisingly affordably by the case; no idea if that's still true. The LF551A is less expensive and still quite highly excellent.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

All in agreement with my past experiences. I just wanted to make sure I wasn't missing anything.

I suspect the reason there may be low-level undercurrents about \6s being found with unusual amounts of sludge is that they are more likely to survive massive amounts of abuse, and thus be found still-running in that condition.
I was born with bragging rights where I need them. Everything else is a distraction.

I'm generally happy with the "regular" WIX filters when I'm in the mood to really care.
Otherwise, I buy whatever is reputable and "one notch up" in quality at Wally's (cheapest place to buy oil I've ever found). I shy away from the cheapest of any of them, and especially the Frams, which had those terrible photos posted all over the webs years ago, though I will buy the higher-level Frams.
I've got a whole bunch of old filters in the weeds by the garage door that I should cut apart some day...

- Eric

I suspect sludge was more of a problem before the advent of PCV valves when engines had draft tubes. That and years of short trips never getting the engine up to temperature to drive off condensation.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

So, like in my 38,000 mile, all-original 103-year-old-lady-owned Dart, which was nevere driven out of her neighborhood, then went to a surfer who would drive it less than a mile to the beach and back on nice days for a few years, and then to a guy who drove it exactly once, around the block, with a mismatched intake manifold and choke spring, which would not let the choke open, for much of that time, at least the past 20 years, but probably closer to 30?

.

- Eric

If it's going to keep you awake at night, pull the oil pan and clean it.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

It ain't.

The valve train area was amazingly clean for a 60 year old minimally maintained engine.

I'll sleep just fine.

- Eric