Saved up oil six oil filters from three daily drivers: 1975, 1975, 1976 slants with 1945's & electronic OEM ignitions. They all are over 100,000 miles, driven 10-16,000 miles each year. Class project was to cut the filter cans open for inspection. All six filter elements had coatings of black carbon "sand" that crumbles between your fingers. These cars are kept fairly well tuned to OEM, but oil changes have been about every 5,000 miles or 6 months. I know when adjusting the valves, the insides of the valve covers are always black. These are now using cheap Costco Chevron 10-40 oil, but even with Quaker State they did the same. I know that all you performance folks have your favorite stuff that you like to use, but for us daily drivers the question is: are we all seeing this black inside old slants? I've always thought that this is just a slant phenomenon, because my Ford 302 truck, using the same oils, never did this. (By the way, class comparisons of 20 filters: Fram filters are junk, Wix are OK, any OEM filters were good quality.)

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"Louise", a 1976 Dart Custom project, (now sadly reverted to being just an "organ donor" to our other project Darts.)

Try going to any brand with the API star 5W-30 weight oil and making sure the engines have the correct temperature thermostat. I have never had an oil filter have carbon in it (but I have never cut one apart- only drained it into my oil drain pan).

Are these motor driven until they get good and hot regularly? PCVs and crank breathers in good shape?

I agree that infrequent driving and not high enough operating temps can cause this. Or, this sludge has been in the engine for 20 yrs and it will take many (and more frequent) oil changes to get rid of it. None of my rebuilt Slant engines have had this crud (including one with 170k miles, rebuilt 1989).

The "old" oils (pre-1980s-90s) had lots of paraffin-type additives and were less controlled as far as what parts of the crude oil were left I them. Deposits were common on all engines.

We might have had more deposits on Slants due to the longer time of warm up and probably more conservative driving habits of Slant owners way back when.

Lou

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Home of Slant6-powered fun machines since 1988

Yeah, they are well maintained. My thoughts come from my experience with piston engined airplanes- short trips and never really getting up to heat long enough to burn out the carbon, which is the case here in Seattle with daily drivers. Thermostats are 195* I think, and seem to be working correctly.

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"Louise", a 1976 Dart Custom project, (now sadly reverted to being just an "organ donor" to our other project Darts.)

What, the engines don't ever have to idle through downtown Seattle at 5 pm?

Once a month (at least) try and take each car out for a long cruise at highway RPMs. At least a 30 minute drive. Let the oil get good and hot and circulate over all the parts.

Way back when I had slants (10 years ago), I used to always run Castrol GTX 10w-30 or 10w-40, and even after 30,000 + miles on a rebuilt motor or totally cleaned out valve cover / head assembly, my engines were super clean inside. I used to always run 180 thermostats too.

But there wasn't much put-putting around town for me and only driving 2 miles a day. My Slants got run as hard as they would go!

Chevron or Quaker State (or Pennzoil) is something I'd never run in one of my engines. After reading that oil filter report years ago I always used Purolator Premium Plus filters, never another Fram for me since then!

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