Hey guys, looking for some advice on what weight oil to use. I have a fresh rebuilt d16, and I thought my bearing tolerances were loose (.0022) so for first fill I used 10W40.

Wrong choice, its very cold were I live right now -10 celcius at nights usually. Upon cold start I get 60+psi, 75+ with a slow rev. After the car is fully warmed up though the idle is @ 15 or so, which Im happy with.

For the cold months, what oil weight do you guys think I should switch to.

I was thinking of looking for an SAE15, or possibly a more common 10W20. Is there such a dragon?

What do you guys think? Ive only had this 10W40 in there for a day but I obviously cant drive the car like this and its gotta go!!

Thanks for any help

 

Make sure you use synthetic, standard oils turn to molasses in cold weather where synthetics are relatively free flowing

The first number is viscosity when cold, second is viscosity when hot, so you might look into a 5w20 or 40 or even a 0w(something) if the lower 5 weight oil doesn't work

 

And a straight weight oil will act the same no matter the temperature which would be worse than what you have now... having a 20w oil in cold temps on a cold motor will cause even worse pressure issues

It's pretty standard practice to change viscosities in winter if it gets cold where you are, so running 10w30 in the hot months, it would normally take a 5w30 if the temps get below 0 to keep oil pressure within range

 

you should be fine with 5w40.

 

60+psi is nothing lol on a cold start on my new motor i was getting 100+psi with rotella T6 5w40 in 70 degree weather.

 

Yea in cold weather during cold starts you'll probably make as much pressure as the oil pump pressure bypass will allow

If it stays to high too long you could damage some seals in places and if you have a turbo with no restrictor, well, that's bad

 

i built my engine with .0016 on the mains and .0018 on the rods, thats why my pressure is high, but its designed for a thinner weight oil

 

Yea you could get away with a lower weight oil just fine for the motor, you just have to consider the viscosity needs of the turbo

 

I guess I dont understand the oil numbers, I thought 10w40 meant 10 was the numbers when warmed up, 40 when cold. Aka starts at 40 thick and warms up to 10 thick.

I think I want to usea dino oil for breakin dont I?

Im confused on what to buy to bring the cold start pressure down, but not go any lower with the idle pressure when warmed up

 

No, first number is cold viscosity, 2nd is hot

Read these links

http://www.upmpg.com/tech_articles/motoroil_viscosity/
http://www.castrol.com/castrol/gener...tentId=7007302
http://en.m.wikipedia.org/wiki/Motor_oil
http://www.bobistheoilguy.com/puttin...into-viscosity

That last link I posted, read through his whole site... really good knowledge base about oils, lubricants, etc

 

5W-30 was the lowest conventional oil I could find off the shelf locally. I was really hoping to find 0W-40 but that is only sold in synthetic and since the motor barely has 20 miles on it I didnt want to go with synthetic obviously

Hope the pressure is good, gonna fill it up right now, real test will be when its below zero tonight i guess

 

there is nothing wrong with your current pressures if you ask me.

in warm weather with 10w-40 i get 75 psi at cold start and at idle 1000 rpm its at 25 psi warm. **** with the rotella 15w-40 and temps around freezing it gets into the 80s on cold start.

what is your oil pressure warm with load on the engine? i think the factory spec for minimum pump output is like 75psi @3000 rpm. id much rather be at spec or a little higher with a restrictor than low