Motor Oil Viscosity [Archive] - GrandAmGT.com Forum

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Mike Jung
03-02-2004, 10:20 PM
What are the pro's & con's of using a thicker grade in the summer time (or a hot climate region) ?

Why is it we in North America (with CAFE) have recommendations for grades like:
for GM -> 0W30 (in the extreme cold), 5W30, 10W30
for Ford & Honda -> 5W20 (semi-synthetic)

When in other countries the same car/engine will recommend heavier grades.
Like LS1 motor (in the Corvette) here recommends Mobil 1 5W30 motor oil; but in other areas: (in the UK) 0W40 synthetic, (in Australlia) 10W40, 15W-40, 15W-50, and 20W-50.
Honda recemmends (in UK) 5W40 semi-synthetic, (in Australlia) 10W30 motor oils.

Why does our owner's manual tell us not to use heavier grades than xW30 ?
Especially in hot climate regions; where the motor oil temperates can get up there & the motor oil gets thinner at the higher temperates.

Alot of European cars recommend 5W40 grades.

Mobil 1 has recently/is releasing Mobil 1 Truck & SUV 5W40 (http://www.mobil.com/USA-English/Lubes/PDS/GLXXENPVLMOMobil_1_Truck_SUV_5W-40.asp), it is re-labelled Mobil Delvac 1 5W-40 (http://www.mobil.com/USA-English/Lubes/PDS/GLXXE2CVLMOMobilDelvac1_5W-40.asp) & put in smaller bottles for consumer usage.
Castrol North America has brought over (made in Belguim) Castrol Syntec 5W40 motor oil (which really is a 'synthetic blend' with like 50% PAOs).

Brendon
03-03-2004, 12:00 AM
Valvoline Synpower also comes in a 5w-40... used that stuff for quite a while :)

Gt00
03-03-2004, 09:58 AM
The thinner the oil you use , the better gas mileage you will get and believe it or not a couple more horsepower . This is due to less viscous friction with the lighter oil . Obviously it flows better when it's cold also , so it starts lubing your engine faster after a cold startup . There has to be a balance here , if you go too light it won't do the job under extreme heat , like in an all out race engine . I use 10/30 in the summer and 5/30 in the winter . The 0/30 oils would be even better for cold weather use . :)

JuanG1226
03-12-2004, 09:58 PM
I have a question. I have about 90,000 miles in my 2001 GT. Is it pointless to start using synthetic oil now? I've heard that the oil is so thin it might slip a seal. If anyone knows would you please let me know. Thanks!

Gt00
03-13-2004, 05:23 PM
Originally posted by JuanG1226
I have a question. I have about 90,000 miles in my 2001 GT. Is it pointless to start using synthetic oil now? I've heard that the oil is so thin it might slip a seal. If anyone knows would you please let me know. Thanks! Check out this thread > http://www.grandamgt.com/forum/showthread.php?s=&threadid=28111&highlight=synthetic+oil

Mike Jung
03-13-2004, 10:33 PM
Originally posted by Gt00
Check out this thread > http://www.grandamgt.com/forum/showthread.php?s=&threadid=28111&highlight=synthetic+oil
Use this link instead (so you can see Pages 2 & 3): http://www.grandamgt.com/forum/showthread.php?s=&threadid=28111

Originally posted by JuanG1226
I have a question. I have about 90,000 miles in my 2001 GT. Is it pointless to start using synthetic oil now? I've heard that the oil is so thin it might slip a seal. If anyone knows would you please let me know. Thanks!
As long as your engine gaskets are in good shape & you have no oil leaks; it should be ok.

You might want to do a engine 'flush' (or a tune-up oil) at/before your next oil change; before going to synthetic motor oil with the amount of miles you have on the engine already. This will help take out any junk coating in the engine & the rings.
or just use the synthetic motor oil: & change the oil & filter earlier (like in 3-months) for the 1st time. As the engine will be in a cleaning phase.

If going with synthetic motor oil; I would go with a real (PAO base) 'synthetic' motor oil, like: Mobil 1 Truck & SUV 5W40, Mobil 1 10W30, Amsoil ATM 10W30, (made in Germany) Castrol Syntec 0W30 (non of the made in USA Castrol Syntec motor oils), etc...
If you got some money, try: Red Line 10W30 (PE Polyol Ester base) synthetic motor oil


If it was me: I would go with a synthetic motor oil :thumbs:

JuanG1226
03-13-2004, 10:51 PM
Thanks Mike Jung. I wasnt sure what to do. I had heard comments for and against using synthetic oil with this many miles on an engine.

Mike Jung
01-20-2005, 09:22 PM
Document ID# 1273140

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Info - Engine Oil Quality and Viscosity (Export Only) #03-00-90-002 - (03/19/2003)
Engine Oil Quality and Viscosity (Export Only)
1994-2003 GM Vehicles with Gasoline or Diesel Engines Operated in Foreign Countries (Outside the United States and Canada)


Notice: Using engine oils of a viscosity other then those viscosities recommended could result in engine damage.


Engine oil viscosity (thickness) has an effect on fuel economy and cold weather operation (starting and oil flow). Lower viscosity engine oils can provide better fuel economy and cold weather performance in colder regions of the world. However, in many regions of the world with higher air temperatures, only higher viscosity engine oils are available. When choosing an engine oil viscosity, consider the air temperature range the vehicle is operating in before the next oil change.

In countries other than the United States and Canada, it may be difficult to find engine oils that display the "API Starburst" symbol certifying the oil for use in gasoline engines. If you are unable to find engine oils displaying the "API Starburst" symbol, use engine oils that meet the API Service "SL" or ACEA A3-02 requirements. Additional engine oil viscosities meeting API Service "SL" or ACEA A3-02 requirements may be used as shown in Figure 1 in accordance with the temperature ranges shown.

In some countries, the majority of the engine oil viscosities shown in Figure 1 may not be available. In those countries, SAE 20W-50 engine oil may be used as long as it meets API Service "SL" or ACEA A3-02 requirements and is used in accordance with the temperature ranges shown.

FIGURE Figure 1 -- Gasoline Engines(c)

(click above link to see figures)

*Engine oil must meet API service SL or ACEA A3-02

**Follow your Owners Manual for the preferred engine oil and oil change interval.

FIGURE Figure 2 -- Diesel Engines(c)

(click above link to see figures)


*If the preferred engine oil is not available, ACEA B3-02, API CH-4 or API CG-4 of the correct viscosity grade should be used. If API CH-4 or API CG-4 oils are used then change the oil and filter every six months or 5000 miles, whichever occurs first.

**Follow your Owners Manual for the preferred engine oil and oil change interval.



GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION


Copyright General Motors Corporation. All Rights Reserved.


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Document ID# 1273140

Mike Jung
01-20-2005, 09:32 PM
...In countries other than the United States and Canada, it may be difficult to find engine oils that display the "API Starburst" symbol certifying the oil for use in gasoline engines. If you are unable to find engine oils displaying the "API Starburst" symbol, use engine oils that meet the API Service "SL" or ACEA A3-02 requirements. Additional engine oil viscosities meeting API Service "SL" or ACEA A3-02 requirements may be used as shown in Figure 1 in accordance with the temperature ranges shown...

*Engine oil must meet API service SL or ACEA A3-02...

How funny they mention European oil spec ACEA A3-'02 :thumbs: ; but in North America they say to use viscosity grade 5W30 API service SL (API service spec's are :vomit: :rolleyes: )

You won't find many 5W30 motor oils that are ACEA A3 rated; almost all of them are thicker than a 30-weight motor oil, like 0/5W40.

I am now using a ACEA A3 rated real 'synthetic' motor oil.
German Castrol Syntec 0W30 synthetic motor oil (that is almost a 40-weight motor oil when at engine operating temperatures).

Note to Mobil 1 users: the only ACEA A3 rated Mobil 1 oil is -> Mobil 1 0W40 synthetic motor oil (the factory-fill for Porsche & Mercede AMG's).
All the other Mobil 1 grades like: 0W30, 5W30, 10W30 synthetic oils are too thin & burn off too easily.