Older vehicles=thicker oils

[TFB1]

Originally Posted By: Doug Hillary
Hi,
perhaps we need to qualify what "Older vehicles" really means.

These are the viscosities specified for some Older vehicles

Early 1930s
>90F = 40
50-90F = 30
15-50F = 20
-15-+15 = SAE10 or 90/10 SAE20 and kero
kero or 80/20 SAE20/kero

In 1940
>90F = 30,40 and limited 50
>32F = 20W, 20, 30
>10F = 10W, 20W
>-10F = 10W
kero

Interesting?


In warmer climates most manufactures recommended a "summer"(160*)thermostat even up into the 1950s, this was mostly to lesson boil off of the alcohol based coolant... In that light, with oil generally reaching a similar temp, actual operating viscosity would have been far greater than in today's engines using 195* plus thermostats... A winter "stat" would have been 180*, so oil still never likely reached the temps we see today...

 

[Topo]

Originally Posted By: OceanDoctor
I'm using 0w20/0w30 blend in the high mileage Camry. Runs as great as it ever has, very quiet also. It sees rather hard driving, most days it'll see pedal to the ground and 170km/h(110mph). I see zero need for thick oil, in fact I changed out QS 5w30 early to get the 0w blend in there.

I should add, oil pressure is excellent. 80-90psi@3000+rpm in -15C weather. >10psi hot idle. 45-50psi@2500rpm hot.


Man oil companies should make a 0W/25 oil.

 

[SS1970chrysler]

Originally Posted By: SteveSRT8
None of you guys have any engines old enough!

On our fleet vans they spec 5w-30, and we use that for the first 150-200k miles. At some point they will begin to consume oil a bit, then we simply go up a grade.

This completely stops consumption. It rarely makes any discernable difference in oil pressure. Frankly we do not worry much about oil pressure anymore.

When was the last time anyone experienced an oil pressure related failure?

My vehicles range from 1939 to 1978. Oddly, the only ones that seemed to need going up a grade in oil were late 70's-early 80's vehicles I've had. A 1979 Thunderbird 351W and an 83 Lincoln MkVI. Both eventually suffered oil psi related failures. In rebuilding those engines, I found the main contributing factor to be timing gear debris plugging the pickup leading to wear of the oil pumps.

 

[SteveSRT8]

^^^ Absolutely true^^^

We used to run Dodges in our fleet in the 80's and the timing gear would almost always shred and plug the oil pump pick up.

But in modern engines (since like 2000 or so) it is very rare to see any failures related to oil pump pressure, it just rarely happens.

 

[SS1970chrysler]

^That reminds me of 2 vehicles we had that also had oil psi issues, but didn't suffer a related failure so cause was officially unknown:
1972 Dart 318 needed 50/50 mix of 10w-30 and 10w-40 to prevent oil light from flickering at stops after highway use.
1992 Plymouth Acclaim 2.9 needed 1 qt 10w-40 in each oil fill to prevent same thing at all stoplights.

 

[CATERHAM]

Originally Posted By: Topo
Originally Posted By: OceanDoctor
I'm using 0w20/0w30 blend in the high mileage Camry. Runs as great as it ever has, very quiet also. It sees rather hard driving, most days it'll see pedal to the ground and 170km/h(110mph). I see zero need for thick oil, in fact I changed out QS 5w30 early to get the 0w blend in there.
I should add, oil pressure is excellent. 80-90psi@3000+rpm in -15C weather. >10psi hot idle. 45-50psi@2500rpm hot.


Man oil companies should make a 0W/25 oil.

They do.
Amsoil 0W-20, RL 0W-20 and RLI 0W-20 all have HTHSV's greater than 2.75cP. Or do what OceanDoctor has done and make your own.