I believe I am running 10W30 in my 3800 SC. But, I believe it should be 5W30, and I am thinking I should switch before winter hits. Believe it or not I have searched and I cant find specifications for oil on the 3800. What are the GM manuals calling for? (I am talking about the engine not the supercharger.)

The cap on the valve cover of the Series II engines says "10W30".

older series II engines called for 10w30 newer ones called for 5w30, honestly going from 10w30 to 5w30 wont do anything bad . in winter i would run 5w30 just because it will start easier, in summer definitely run 10w30 as long as mornings are above 30* F
the original owners manual specifies a range of different viscosity oils that are suitable: the lower the first number the colder the operating range of the oil, the second number is the viscosity when the engine hits operating temp, and should not change unless the engine is expected to run excessively hot.
so 5w30 for winter and 10w30 for summer will bring you the longest living engine...
yes this is for all series 2 engines (supercharged and naturally aspirated)
the supercharger uses a special oil that i have no idea yet what is in it, but it smells like axle fluid (80w90)

[This message has been edited by BlackGT Codde (edited 09-12-2011).]

10w30 or higher.

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Turbo 3800 E85 5spd spec5
11.53@126.7

The confusion for me comes about because I had a 97 GTP and I remember changing the oil -- 5W30. My Fiero 3800SC, year 1996, says 10W30. If the engines are the same, it seems GM changed there oil recommendations. I will go with 5W30, should help with turning it over, especially when it gets colder out.

Thanks for clearing this up.

I,ve used Mobil One 5W30 exclusively in my 3800SC series III . The only negative thing about this grade of synthetic is that it will find the slightest leak point. It seems to protect the engine fine but for heavy strip use I would lean towards10W30.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, ZZP Intercooler, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

At least Series 3 asks for 5w-30. Found the explanation below at: http://www.carkb.com/Uwe/Fo...1595/3800-Series-III
It looks reliable to me.

5W-30 ENGINE OIL
The recommended lubricant for the 3800 Series III is 5W-30 oil, compared
to 10W-30 in previous 3800s. With the lighter oil, the maximum change
interval does not change. GM’s industry-leading Oil Life Monitor still
calculates oil life based on a number of variables, including engine
speed, operating temperature, load or rpm variance and period of
operation at any given load and temperature, and then recommends a
change when it’s actually needed, rather than by some pre-determined
interval. The owner’s manual in cars equipped with the 3800 Series III
will continue to recommend an oil change at least once a year.

The change in lubricant was driven by efficiencies in the engine and
near-universal availability of the new GF-3 standard engine oil.
GF-3 uses a new refining process, and it contains a friction modifier,
meaning that that at a given weight or viscosity, it's more resistant to
breakdown with heat. The 5W-30 engine oil is more efficient in cold
ambient temperatures. It creates less friction or fluid resistance when
the engine is cold, requiring less cranking power and reducing fuel
consumption during cold starts. The 5W-30 oil also reaches its most
efficient operating temperature more quickly that 10W-30.