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Old 10-02-2016, 09:39 AM   #1
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Default Oil viscosity for ls2 in hot weather ?

Hello


I have pontiac g8

With high pressure melling oil pump 10295

I used valvoline armour 10w40

The pressure 35 psi on hot idle


My qusetion : in my place the weather all time 45 c outside temp ,, only one month in winter it is minimum 8 c on morning

Does my oil fine ? Or switch to 5w40 ?

Dealer say 5 w30 but before my pressure 16 psi on 5w30
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Old 10-02-2016, 10:03 AM   #2
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The primary difference between 5w40 and 10w40 is the cold temperature viscosity. At operating temperature, their characteristics should be the same. The colder the oil is, the thicker it will be. If it does get cold, and you keep 10w40 that you have been running, you can typically avoid trouble by babying it until the car comes up to operating temperature and the oil pressure starts to level out.

With that brings a whole different concern however, why are you running thicker oil? What modifications do you have that necessitate it? As I understand it, the high oil pressure kits simply raise the relief pressure that bleeds off excess oil pressure. 16 psi at 45c at idle isn't exactly the end of the world, provided it raises as the engine speed comes up.

If the engine is relatively stock, and you routinely deal with oil thinning due to excessive temperatures, it may be worth considering a means of monitoring oil temperature, as well as increasing the engine oil cooling capabilities of the car. High oil pressure can be as big of a concern as low oil pressure.
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Old 10-02-2016, 11:02 AM   #3
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Quote:
Originally Posted by rjolly87 View Post
The primary difference between 5w40 and 10w40 is the cold temperature viscosity. At operating temperature, their characteristics should be the same. The colder the oil is, the thicker it will be. If it does get cold, and you keep 10w40 that you have been running, you can typically avoid trouble by babying it until the car comes up to operating temperature and the oil pressure starts to level out.

With that brings a whole different concern however, why are you running thicker oil? What modifications do you have that necessitate it? As I understand it, the high oil pressure kits simply raise the relief pressure that bleeds off excess oil pressure. 16 psi at 45c at idle isn't exactly the end of the world, provided it raises as the engine speed comes up.

If the engine is relatively stock, and you routinely deal with oil thinning due to excessive temperatures, it may be worth considering a means of monitoring oil temperature, as well as increasing the engine oil cooling capabilities of the car. High oil pressure can be as big of a concern as low oil pressure.
Thanx ..

Coz i feel the outside temp is more than as manual owener say like 5w30

I talking with u sometimes it kicks 50 degrees outside

So .. i heard many people that 16 psi will damage the engine and will affect on the stock cam and valve lifters

I don have any tick noise


My Q: depend the bad weather here .. it is ok to switch with 5w40 ? Coz 10w40 more thicker
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Old 10-02-2016, 11:04 AM   #4
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Thanx ..

Coz i feel the outside temp is more than as manual owener say like 5w30

I talking with u sometimes it kicks 50 degrees outside

So .. i heard many people that 16 psi will damage the engine and will affect on the stock cam and valve lifters

I don have any tick noise


My Q: depend the bad weather here .. it is ok to switch with 5w40 ? Coz 10w40 more thicker

My car is only long headers and afe air filter with basic tune
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Old 10-02-2016, 12:56 PM   #5
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There is a general rule on the internet that suggests 10psi of oil pressure per 1k RPM is acceptable, with ventures above 40psi not generally being of any benefit.

I see no issue with 15psi of oil pressure at hot idle. Now, there would be an issue if that was 15psi at 3k RPM.

Even the internet suggests that GM service allows the following oil pressures for the LS2:
6 psi @ 1000 rpm
18psi @ 2000 rpm
24psi @ 4000 rpm

I am still not convinced you need anything beyond the manufacturer'* recommendations.

As I mentioned before however, the difference between 5w40 and 10w40 is the cold performance. If you feel the oil pressure is too high in the cooler months at cold start, then that could be a motivator to make the switch.

Then again, LS2 is not my area of expertise. I await the chiming in of others with more application specific knowledge.
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Old 10-02-2016, 01:14 PM   #6
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Quote:
Originally Posted by rjolly87 View Post
There is a general rule on the internet that suggests 10psi of oil pressure per 1k RPM is acceptable, with ventures above 40psi not generally being of any benefit.

I see no issue with 15psi of oil pressure at hot idle. Now, there would be an issue if that was 15psi at 3k RPM.

Even the internet suggests that GM service allows the following oil pressures for the LS2:
6 psi @ 1000 rpm
18psi @ 2000 rpm
24psi @ 4000 rpm

I am still not convinced you need anything beyond the manufacturer'* recommendations.

As I mentioned before however, the difference between 5w40 and 10w40 is the cold performance. If you feel the oil pressure is too high in the cooler months at cold start, then that could be a motivator to make the switch.

Then again, LS2 is not my area of expertise. I await the chiming in of others with more application specific knowledge.
U realy help me .. and u give me the right things that i am searching
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Old 10-03-2016, 08:06 AM   #7
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I have a 99 Trans Am running at 575 HP, and run 10W30. Keep in mind higher pressure means less flow. Since your issue is hot weather, not cold, switching to 5W is that opposite of what you should do. Are you running synthetic oil? Do you monitor oil temperatures?
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Old 10-03-2016, 08:31 AM   #8
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Originally Posted by 2kg4u View Post
I have a 99 Trans Am running at 575 HP, and run 10W30. Keep in mind higher pressure means less flow. Since your issue is hot weather, not cold, switching to 5W is that opposite of what you should do. Are you running synthetic oil? Do you monitor oil temperatures?

Hello

Now i am using valvoline 10w40 synthetic blend Vicosity @100 c= 14,9 and dexos arround 11

About the monitor of oil .. i can observe it today and put it here


so ur talking to keep my thick oil or switch ?

Wait me for oil temp
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Old 10-03-2016, 11:05 AM   #9
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Your owner'* manual states you should use 5W-30 at all operating temperatures, and specifically states "Do not use SAE 10W-40, SAE 20W-50 or any other viscosity grade oil not recommended".


You should run 5W-30.
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Old 10-03-2016, 12:37 PM   #10
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Quote:
Originally Posted by 2kg4u View Post
Your owner'* manual states you should use 5W-30 at all operating temperatures, and specifically states "Do not use SAE 10W-40, SAE 20W-50 or any other viscosity grade oil not recommended".


You should run 5W-30.
So outside temp dosent matter
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