0w40 + 0w20 mix works well to quite 4L SOHC

[FordJimbo]

My 98 4L SOHC with 206k miles has the rattle for 1-2 seconds on startup, and idles a little rough. It has otherwise been well maintained by me, with new plugs and wires, PCV, cleaned MAF and new EGR, lots of regular oil changes recently.

I'm out of 5w30 (recommended oil) but flush in Amazon A3/B4 certified European 0w40 and Castrol black bottle high mileage with titanium 0w20. I decided to take a chance and brew a 50/50 mix aiming for a 30 weight. I can report that it actually did quiet down the cold startup rattle about 80% to almost nothing, and it idles a bit smoother. I'm actually quite impressed with this "free" mix I had on hand. I also have some Castrol 0w40 so I'll mix the Castrols next. Or I might try Castrol 0w40 straight. Grok AI suggested these options as suitable for aiding these symptoms and otherwise suggests, and I have a theory that it's either the 0w for faster cold flow to the top of the engine, and/or the titanium fluid bond might be the magic that timing chains and tensioners need to assist in cold startups. I like this 0w30 mix as it has some European certs while also having the faster cold flow of a 0w and seal conditioners of a high mileage oil.

Anyone with cold startup rattle might try the Castrol 0w30 (or a mix to achieve that with 50/50 0w40 and 0w20) with titanium. Or a straight up 0w40. I don't think there's a high mileage version of 0w40 but I could be wrong. I like the high mileage additives in my high mileage vehicles.

 

[C420sailor]

I run 5W40 in my engines. Seems to be a good balance. It’s personal technique only, though—everyone does their own thing.

Fair warning though, the rash of Chevy V8 failures are being attributed to a change from 5W to 0W. That stuff is THIN.

I’d sooner run a heavier oil closer to factory spec and switch to mechanical tensioners. That upgrade completely silenced my valvetrain.

 

[Fix4Dirt]

I run 5W40 in my engines. Seems to be a good balance. It’s personal technique only, though—everyone does their own thing.

Fair warning though, the rash of Chevy V8 failures are being attributed to a change from 5W to 0W. That stuff is THIN.

I’d sooner run a heavier oil closer to factory spec and switch to mechanical tensioners. That upgrade completely silenced my valvetrain.

I saw 0-16 the other day... I think it just might be thinner than water! And I thought 0-20 was as low as we could go ahha

 

[C420sailor]

I read somewhere that the change to 0W oils is for EPA mileage. It’s gaining about 2-3% in fuel efficiency in exchange for about a 30% decrease in engine life.


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