[MYBAD79]

OK... today's advendture on I95:

It was very hot today and my engine temp went up to roughly 225F. Normally it doesn't go above 210F (center mark on the gauge) but today I had to turn the AC off so that the temp stays at 210F.....
Well, I turned the AC on and off as the engine temperature allowed, it went up to 225 a few times and then back to 200-210 when I turned the AC off and slowed down to reduce engine rpm....
I noticed that my oil pressure was only 50psi today, normally it's 60 and higher. Usually it's 40psi at idle, today when pulling into a gas station I noticed it's 30psi at idle :crazy:

I let the engine cool down and checked oil pressure: now it's back to normal, 40 at idle and 60 when driving.

I changed my oil about 4 weeks ago. castrol synthetic blend 5W30 was on sale - it was a good deal and I bought it instead of the 10W40 that I usually use (Castrol or Valvoline synth blend) .....

Now my questions:
Is 5W30 too thin at 225F engine/water temperature ?
Should I be worried ?? Engine runs fine now that it's cooler... I went back on the highway and the temp didn't exceed 210F....

 

[DeeVeeEight]

I'm no expert, but I would save the 5W 30 for the winter months and go with a 10W 40, or even a 20W 50 for an older engine in the hot weather. I don't think that you have done any damage, but you did see the oil thin out a bit when your oil pressure dropped slightly.

 

[jotape650]

dude no worries i live in miami and my 79 was running hot and oil viscocity does get thinner as temps rise. You should resolve your cooling issue especially when running the a/c. Tomrow im receiving my alum. radiator and fan so hopefully that solves my issue. Down here with the a/c off it would run bout 220.!

 

[mrvette]

I prefurr oils to be 10w30 in winter...and 30w90 in summer....:crazy: :devil:

the latter being somwhat hard to obtain is helped by thick oil treatments...IE...GEAR oil STP in the tiney expensive bottle has held many an olde tyred engine together for a few more years....over the decades....

but summer is 20-50 and winter is typically 10-30 something like that...

I am amazed the cooling affect of the oil pan/engine from airlflow alone

as with the water temps being relatively close...there is no other expalaination over the oil pressures....and it's VERY consistant...

:thumbsup: :cheers:

 

[turtlevette]

sounds like you need an aluminum radiator.

that's too hot.

Mine runs about 180 on the hwy but, i don't have the luxury of A/C.

 

[Bangkok Dean]

I use Amsoil 20W40 year round as here the average temps are high 90s.
In traffic with the AC on the engine temps rise to 210 but I have two extra fans on a switch that push air threw the AC and radiator. The switch also kicks up the rpms to 1,000. So in traffic or long lights on hot days I just hit the switch. BTW I am still running the original radiator.

Now my Harley I can't use synthetic oil it gets too thin and the lifters collapse, even the HD dealer has stopper using synthetic oils in South east Asia due to the high temps here. The straight 50 or 60 weight seams to be the best here.:cheers:

 

[TwinTurbo]

better get some 40 did you check w/ the manual what the rec. oil pressures are? No need to panic until it goes below 10psi/1Krpm

 

[rjent]

better get some 40

God I hate the multivis oils. This is just a good example of why .....

I think you will be amazed as to the difference in oil pressure with the straight 50W in that kind of heat.

As always JMHO! :laughing:

 

[TwinTurbo]

10W50 will produce the same hot pressure as your straight 50 weight.

What is the example here for not liking multiGRADE oils? He just chose the wrong oil for his operating temperatures, it has nothing to do with being a multigrade.

 

[Elduderino]

Are you all sure the notch in the gauge between the 100 and 220 is 210?

I just figured it was 180 or 190.

Can anyone confirm its 210?

 

[jotape650]

id figure it would be 160. lol simple math

 

[MAVEN]

First thing we need to realize here is that factory gauges are merely rough estimates. If you want to use the gauge you use it like this...its good until its in the red. If you want to actually know youre coolant temp purchase a gauge designed for the purpose from a reputable company. 30psi oil pressure at idle when hot on a small block with 5w30 is GREAT oil pressure. (spec for most smallblocks is 6spi/1000rpm, 18psi/2000rpm, 24psi/4000rpm at full operating temperature)

5w30 or 10w30 is likely what youre engine calls for, If you wanna use 10w40, id say go for it, wont hurt anything, id stay clear of things like SAE50 and any of the aforementioned 30w90's unless of course if your running this this HARD and HOT all the time.(I dont know of anyone who seriously uses anything thicker than 50, or maybe 60 in super extreme high temperature situations, like racing in Dubai )

 

[turtlevette]

10W50 will produce the same hot pressure as your straight 50 weight.

.

In theory. But it doesn't ever seem to work out that way. Why are synthetics so thin? Dean said it won't work in his Harley and i believe him.

When i purchased by Grand National they made me sign an agreement to run straight 30W oil in it. I went ahead and did what i thought was best and ran Mobil 1 5w30 but i bet there was some good reason for it.

I would recommend a synthetic 0w20 or 0w30 for your car. You will never get 3 gallons of oil hot. And it you do its going to cook you to a nice well done crispy with the tank (keg) being right behind your head.

 

[rjent]

10W50 will produce the same hot pressure as your straight 50 weight.

What is the example here for not liking multiGRADE oils? He just chose the wrong oil for his operating temperatures, it has nothing to do with being a multigrade.

Well sir, I simply don't agree. What he experienced is what happens to all multivis oils. They simply can't maintain the viscosity of a straight oil. (see my post here in another thread. I have run both types of oil for over 40 years and like I have said before, I have always witnessed a difference in oil pressure between straight and multivis. Yes multivis operates in a wider range of ambient temperatures, but there is still a loss of oil pressure across the board because of the polymers. I have always felt uncomfortable with that loss of oil pressure. I see it in my airplanes, I saw it in my race cars, and I see it in my street cars. With my new vehicles I run what the manufacture reccommends, but my hotrods are straight viscosity all the way.

Just my experience ... :huh:

 

[cortlandfire]

OK... today's advendture on I95:

It was very hot today and my engine temp went up to roughly 225F. Normally it doesn't go above 210F (center mark on the gauge) but today I had to turn the AC off so that the temp stays at 210F.....
Well, I turned the AC on and off as the engine temperature allowed, it went up to 225 a few times and then back to 200-210 when I turned the AC off and slowed down to reduce engine rpm....
I noticed that my oil pressure was only 50psi today, normally it's 60 and higher. Usually it's 40psi at idle, today when pulling into a gas station I noticed it's 30psi at idle :crazy:

I let the engine cool down and checked oil pressure: now it's back to normal, 40 at idle and 60 when driving.

I changed my oil about 4 weeks ago. castrol synthetic blend 5W30 was on sale - it was a good deal and I bought it instead of the 10W40 that I usually use (Castrol or Valvoline synth blend) .....

Now my questions:
Is 5W30 too thin at 225F engine/water temperature ?
Should I be worried ?? Engine runs fine now that it's cooler... I went back on the highway and the temp didn't exceed 210F....

i added (wetter water) to mine , cooled it 10deg.,,can be gotten any auto store.

 

[TwinTurbo]

10W40 passes the viscosity test for a 40 grade @ 100C, wether it's synthetic or dyno oil. It doesn't pass the 50 grade test, therefore it's classified as 40. This means the viscosity @ that temperature is about the same, otherwise the flow test results would not be the same.

Synthetics are not thinner,

The tank will sit behind a fireall, I'm goign to separate the rear area from the passenger compartment. As for the oil being hot, the system has an adjustable cooler bypass and a thermostatic bypass. Remember, those 2 turbos will increase the oil temp significantly. I also have blankets for the lines and the tank.

The synthetics are thin thing comes from the cold flowing capabilities. Since synthetics are engineered and formed from bsae stocks by chemical reactions they don't have contaminants like sulphur and asphalts and also don't sludge and varnish. Since there's no wax in it it will flow much better at cold temperatures. this means that you can have base oils w/ 5 or even 0w gradations. With minerals this is not possible.

Synthetics have developed significantly over the years. Initially they were di-esters, later they were poly-ester based. The problem w/ di esters is that all molecules are compromised of similar molecular bonds, if your oil then reaches a temperature high enough to break the bonds the whole bolk of the oil that reaches that temp suddenly disintegrates, it thins out and becomes useless. With a polyester based olil there are many different bonds, some stronger some weaker. The weakest links go first leaving you with a funnctional bulk even if the weakest bonds break down. Initially these polyester based oils were very expensive and not available to the public. You have to view those manuf. recommendations in light of when they were issued, problems like above may be the reason for that.

As for the harley example, IMO this is very weird. Synthetics don't break down and thin out as much @ high temps as dyno oils. IN a very high temp environment it would be the synthetic that would be the oil of choice. There must be another reason apart from viscosity or oil thinning for the issue. Maybe it's barrier protection or dispergants. VI @ high temps can cause problems w/ dyno oils, not so much w/ synthetics.
With an air cooled engine especially the rear cylinder gets hot. I wouldn't be surprised if the oil got up to 240 deg or so. In those circumstances oxidation, thinning and forming of sludge and sooth is a big issue with mineral oils. Synethtics are a much better choice in such circumstances with their better resistance to higher temps and sludge forming. It really doesn't make a lot of sense. Maybe HD is pushing the dyno oil for a different reason?

Maybe it's the "slipperyness" that is causing the problems?

 

[yellow73sb]

I have 70+ psi and it never goes below that even at idle

I have a washer in the output of my pump that restricts it and the oil pressure stays up. It's my uncle told us to do. Hes been racing for a looooong time

I have the m55hv

 

[turtlevette]

The tank will sit behind a fireall, I'm goign to separate the rear area from the passenger compartment. As for the oil being hot, the system has an adjustable cooler bypass and a thermostatic bypass. Remember, those 2 turbos will increase the oil temp significantly. I also have blankets for the lines and the tank.
?

You have 3 gallons of oil to heat up. That is going to take a long time regardless of whether you have an oil cooler bypass or not. You're almost going to have to putt around for 30 min to get the oil warm before you start getting into boost.

 

[turtlevette]

I have 70+ psi and it never goes below that even at idle

I have a washer in the output of my pump that restricts it and the oil pressure stays up. It's my uncle told us to do. Hes been racing for a looooong time

I have the m55hv

That doesn't make sense Chris, Ask him again why.

 

[TwinTurbo]

You have 3 gallons of oil to heat up. That is going to take a long time regardless of whether you have an oil cooler bypass or not. You're almost going to have to putt around for 30 min to get the oil warm before you start getting into boost.

The tank has 2 heater blankets and 2 heater elements inside so warming up the oil on cold days isn't a problem. I can shut down the oil coolers so the system only gets oil straight from the tank. I't shouldn't matter a whole lot if the oil is in the tank or in the sump. If the oil stays too cold i can always run less oil in the tank, not a problem at all.