Synthetic oil in J series V6 engines.

[NVA-AV6]

At least what I have observed-

Syn oil seems to thin out alot more that conventional with heat. A example of this was with Kschwiggy's car, he has a AEM oil pressure gauge and a built J35. With Mobil 1 5W20 at full operating temp at Idle he was only getting 7psi of oil pressure, now the same engine with Castrol 10W-30 again at full temp at idle was getting 15-17PSI. The factory spec for these engines is 10PSI minimum although I like the 15+ PSI much better, now this lack of pressure means that oil is not providing great protection for the bearings, but more imortantly as in Kevin's case, was not producing a good oil layer on the cylinder walls, this oil is squirted on by small jets on the ends of the connecting rods, without sufficent pressure a incomplete layer of oil will be put on the sleeves and they will eventually wear out (as was seen in Kevin's engine when we swapped his heads). Now before everyone points out the weight difference in the oil, 5W-20 Castrol was also put into this engine and got to 10-12PSI, but again I prefer the higher pressure.

[Mike]

Great information Paul so from what I read here you reccomend running conventional 10W-30 in J series motors?

[NVA-AV6]

From the informal test I have done, yes, I would rather lose 1-2WHP and 1-2MPG and have longevity in my engine.......

[jobata23]

so paul, right now im using syn mobil 5w20 and im in Las Vegas, temp reaches above 100, should i switch to 5w30 mobil syn? and should i stick with mobil one or get a different brand like castrol?

[wtcii]

Do you know anything about the K Series? I have been running either Mobil 1 5w-20 or 5w-30 since I got the car.

[NVA-AV6]

Do you know anything about the K Series? I have been running either Mobil 1 5w-20 or 5w-30 since I got the car.

Once Blinx gets all his gauges re-installed I can run the same test with his car.

That's your call, I would be using a conventional 10-30 if it was me. Synthetic oil historically has had temperature thinning issues all the way back to WWII when Germany first tried using it in thier fighter aircraft engines.

[jobata23]

would it make a big difference if i use 5w30 instead 5w20, i just want more protection.

[NVA-AV6]

Not much....

[kSchwiggy]

now I've been using 10W 30 (castrol or Mobil 1) and at idle it sits with almost 20psi, even after running for a while.  cruising i see about 40-60 psi... and acceleration is never anything short of 80psi

[AV6NHBP6SPD]

so i guess i should switch from 0w-30 amsoil synthetic
so except for Dyno oil, what else can i use. my car is almost at 80k



Paul. is it fair to compare oil pressure with different specs oils? 5w20 and 10w30? i mean as i would think, it would be fair to compare synthetic 5w20 to conventional 5w20?
from that i can see that you recommend using higher viscosity oils, but it doesn t mean you can use synthetic. or where is my though wrong,

would any of effects of using synthetic show up on oil analysis? i would think if it wears our cylinder walls it would show up as higher number of some kinda metal in analysis

[kSchwiggy]

i think what paul is saying... for the purposes of oil PSI, is that comparing dino and syn oils of the same specs (ie 5w20), the synth oil will thin out quicker and yield less lubrication over longer operating times.  using a higher spec (ie 10w30) synth oil would remedy this problem though.... right now I'm running mobil 1 10w30 and the oil remains at higher psi just fine.

[AV6NHBP6SPD]

so if i run for example 10W30 synthetic, it will be fine?

[thisaznboi88]

?? Man this is interesting. Let me know what I should run also for my new v6.

Also I read on k20a that the K-serial have really hight oil pressure. I am not sure if that is true or not.

[timot_one]

Do you know anything about the K Series? I have been running either Mobil 1 5w-20 or 5w-30 since I got the car.

Once Blinx gets all his gauges re-installed I can run the same test with his car.

I'm running an oil pressure gauge right now.  Let me know how you want me to run the tests and I'd be glad to share the results with you.

[NVA-AV6]

Pretty much we are looking for the OP at idle with the car haven been driven fairly hard and fully at temp.