"Vehicles equipped with high performance 318-4bbl engine"

ChryslerCruiser

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Just found in a 'new to me' owners manual for an '87 5th Ave.

Page 80, it suggest that any type of high speed driving, or rapid acceleration requires SAE 30 or SAE 40 oil.

And or, 20W40, Or 20W-50 may be used.


What in the world is going on here? I can not imagine how an extra 25 HP is gonna spin a bearing, or hang a valve..

What are your thoughts, and what weight of oil would you use in the spring-summer-fall months in 45 to 85 degree weather?
 

Aspen500

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That was written with 1987 oil in mind. Since then, oil has come a long way. I'd run either 10W30 or 10W40, either is fine for 45-85 degrees. For normal driving, 10W30 (or even 5W30) will be good. For frequent "spirited" driving, 10W40. If it was driven in winter at -25 to 30 degrees, 5W30 would be much better. Better still, especially in winter, is synthetic oil. Try pouring 5W30 conventional at zero degrees and it's like molasses. Synthetic 5W30 pours like it's 70 degrees out. Quicker oil pressure on start up AND, the engine will start much easier since the starter will be able to spin it over at quite a bit higher rpm. Single weight oil is more specified for lawnmowers or snowblowers these days.
 

ChryslerCruiser

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Ok, Good to hear, and know. Thank You. I'll go with 10W40 on the next oil change, even tho I am far from a spirited driver.

I don't know much about the changes in oil, other than the arrival of synthetic being a good thing from an ease of starting point of view.

I use synthetic in the winter on all of my 'winter rigs' including the generator which is a pull start, and it does make a world of difference.
 

Aspen500

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In the past 35 years the oil has become cleaner (better refined) but it's the additives that make the biggest improvements. Heavier weight doesn't necessarily mean better protection or better lubrication.

Apples to oranges obviously but a lot of newer engines take 5W20, 0W20 or even 0W16 oil but of course, they are designed for that too. Engines are built to WAY closer tolerances now than 20, 30, 50 years ago. Add variable valve timing which uses oil and oil pressure to operate the cam actuators and using the specified weight oil is very important. None of that applies to our cars though, so I'll shut up about it now, lol!
 

XfbodyX

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I understand oil has come a long way but I think the most important aspect of our older v8-s with miles on them has been overlooked.

Viscosity is the most single important thing to our old V8-s. Just like a modern small clearance motor lives well on 0-20 it would not last long on 15-40 because it was not designed to.

Even current oil for high mileage motors 75k and above of the three main things they offer, one is a viscosity modifier to prevent premature viscosity breakdown.

To maintain the oil film between the bearing and shaft so the bearing isn’t starved for lubrication. This also requires more oil pressure from the oil pump and/or more oil volume. Running a thinner oil does not achieve this. The piston ring design, gaps, and the pil control ring was not designed to deal with a thin oil.

The 80-s 318 spec the same clearances as a 1972 318.

Even modern engines with high miles are subject to needing a bit more viscosity.
What makes high-mileage engine oils different?


High-mileage oils have ingredients to take care of older engines, like conditioners, seal swells, antioxidants, detergents and wear or friction additives. Typically they use a viscosity modifier that is durable and won’t lose viscosity very easily. These oils need to stay thicker longer to protect engine parts.
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I myself will never use a modern synthetic in an dino designed motor, 15-40 rotella T4 minimum.

We may not like the stresses thick oil put on parts but we cant dispute the reasons why it is needed by the engine design itself. And most folks are running aged semi high mile motors.

Yep, if it was above 0 we could still and would run straight 30 weight and so it cranked slow, it was expected. For 100 degree summer heat 40 or if it was real loose straight casrtrol gtx 50 weight. Thick and green.


The only reason a mostly stock 318 fmj car really can go against the grain is the gearing produces a very low rpm at even highway speeds. Take a 318 with 125 more hp, 3:91s to 4:56 gears and run down the highway at 3k or bettr rpm with a 10w anything and budget for a crank kit.

Im not saying Asp500 is wrong but I will say our older motors most important oil requirement is based on viscosity and although modern oils have came a long way the viscosity rating system has remained contestant since 1952 although the SAE ratings started in approx 1911 but was modified in 52.

So if you are going to run a 10w oil id consider the high mileage version.

Oil is always a controversial topic :)
 

XfbodyX

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Here is a good question I could not find the answer to. Does newer conventional oil have a faster rate of viscosity change then the 1980 oil? Is that even a valid question?

I know many even run synthetic in there old cars. I for some reason cant.
 

Mikes5thAve

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I've always run 10w30 all year round in these cars snd it's never been a problem. Always plain oil, not synthetic or high mileage or anything special.
The first winter that I drove something newer the first time temps dropped down to near -40 it wouldn't start and i had to switch it over to 5w30 which wasn't fun in that cold. I never made that mistake again...
 

Aspen500

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Yeah, I didn't mean to say run 5W30 in an older car, especially with high miles. Depending on temp, 10W30 or 10W40 for stock engines, maybe 15W40 in mildly modified or with a frequent heavy right foot (lol) or even 20W50 in some cases, or as X said, a high mileage oil.

For the viscosity change question, I have no idea. The "old" car I run synthetic (5W30 since it basically a winter only vehicle) in is my '96 Dakota and it's had only synthetic since it's first oil change. Also of course, synthetic in the '08 Mustang V-6 also 5W30 since it was built for that weight oil. The Aspen gets 15W40 Rotella conventional for reasons cited above.

If you put 15W40 in a modern engine, or even 10W40, first thing you'd have is a check engine light with cam/crank correlation codes due to the oil being too thick to correctly operate the cam actuators. Some that specify 5W20 have problems if 5W30 is put in, or even 5W20 if they want 0W20. They're picky SOB's. :) Sucks for shops because we have to have so many different weight of oil. Wrong topic so I won't even go into all the different coolant types......................:rolleyes:
 
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