I own a 2008 Buick La Crosse Super with the 5.3 V8 engine. The owners manual calls out 5W-30 for ALL temperatures. There is no call out for 10W-30. Evidently for 2008 GM has gone over to 5W-30 as the all temperature oil.

Let me say a few things as a Mechanical enginer the part of the oil viscolity - 5W or 10W - is the performance of the oil at either zero F or zero C. The second number - 30 - is the viscoity of the oil at 212F. The "W" stands for winter not weight.

The Society of Automotive engineers called out allowable viscosity ranges for 5W and 10W. If you look at the allowable range the same oil can be bottled as 5W or 10W and still be in spec. The 5W will be at the high end of the range and the 10W will be at the low end of the range.

For the second number the oil has to have a viscoity within a range to be called "30".

When I was in college a guy from the American Petrolium Institute came to school and talked about the new "energy conserving" logo for oil. Before that program most people in the USA were using 10W-40 oil. This engineer talked how higher numbers protected better. He talked that 5W and 10W both worked the same EXCEPT for main bearing wear on start up. In the standardized SAE test the 5W oil had 4 times the bearing wear of 10W oil.

Since most of us operate our vehicles at temperature after the fast warm up of our aluminum engines the oil has to be flowing like a 30 weight oil.

I recall the writing about how 40 weight oil was bad in the late 80s, the talk about 5W oil sounds like the similar campain by some 20 years later. I can tell you from the API engineers talk the API will make sure oils will operate and protect the equipment they are designated for use. In the early 80s engine oil was reformulated because a certain group of cadillacs towning a trailer in the desert would destry themselves because the engine oil was lacking. He also talked of other addatives for oil but certain vehicles can not use those. If you notice the rating SM/CF tell what what year and older vehicles that oil can be used in.

Here is some info on engine oil from API
http://www.api.org/certifications/en...lGuide2006.pdf

I am using Mobil 1 5W-30 oil in my 2008 Lacrosse Super. As an engineer I know I will have more wear on start up but it is the ONLY OIL called out in the owners manual. I did my first oil change and 2000 miles with 67 oil life remaining. I will now use the oil life meter and run it 10 percent or lower. When it comes to filters I use AC Delco, Mobil 1, puroilator, and would use a Wix.

 

bump

 

I'm due for an oil change tonight. I'm going to go ahead and switch to Mobile 1 Synthetic and continue to use AC Delco oil filters, I'm also going to start changing my oil when the OLM says to, instead of every 3K miles.

 

OLM??

 

Oil Life Monitor - it's displayed in the DIC...

 

OHHH.

When I read "OLM" it didn't click.

My Oil Life is at 87% right now.

 

Mines at 68% right now and I've almost got 3K miles on it.

 

They spec'd 5W based off projected temperature zones that the 85 percentile will operate the vehicle under. My understanding was 10W was better for high heat abuse associated with "heavy duty usage" conditions. The way I drive would fall under those guidelines.

I only use synthetic and semi-synthetic 10W-30 in my cars, but I should probably switch to the 5W in the winter here based off lowest temperature rating.

 

10w 30w Mobil1 with Mobil1 filter I was burning 5w 30w 1/2 quart ever 1500 miles techs in the shop said 10w 30w in the summer

 

beat on it every once and a while, will help reset the rings, and slow oil consumption.

 

Its not uncommon for GM engines to go through a quart of fully synthetic oil between oil changes ( every 3k miles) Synthetic oil is very slippery and small amounts slip past the rings into the combustion chamber, burns and is passed out the exhaust. Its so minute you'll never notice. Many GM techs have told me this since I started using fully synthetic oil years ago.

 

valvoline 10w30 and purolator filter and i change it when my oil life monitor tells me to. guess you folks all think im a heathen

 

When it comes time, I think I'm going with Royal purple 10w-30 and either a WIX filter or a K&N filter.