I just changed the oil in my '97 GMC half ton yesterday. It takes five litres (quarts?) and I found a 5 litre container at my local big box...nice! It wasn't until afterwards that I noticed it's 5-20 wt, not the 5-30 I usually use. Summer temperatures here usually range from 75-95 F (20's-30's C). Do I need to change my oil again?

You didn't say how many miles nor what kind of service you put it through. It is 14 years old and if it has over 100,000 I would be inclined to say yes

Change it and pour in what is recomended.My mother's 2006 Chrysler 300C,have use 5w20 or the MDS system will not work right,has the 5.7 hemi.If you ever hear anyone saying you can mix a quart of synthetic with convential is good turning it into synthetic oil,they are dead wrong.Don't ever mix synthetic with convential  oil,turns to sludge and I have seen this.Pulled the oil pan off a 2001 Bonneville,the pan was full of sludge since the owner poured in a quart of synthetic oil with regular oil every oil change.Surprised the engine did not burn up.

I'd change it and the filter.  Soon. 

When the engine comes to opearting temp, your oil is too thin.  It won't cause any immeidate damage, but the longer it's in there, the greater the chances of damaging the internal parts.

Viscosity is determined by measuring how quickly the oil flow through an orifice at a specific temperature.  The lower the number, the easier it flows.  I'm not positive - it's been awhile, but viscosity is measured/determined at a temperature of 200 degrees.

Anyone else remember the great article that "Slug-guner" posted on here about Motor Oil and Filters. If the Search feature is working that old post would answer the question and then some.

Not sure but here is one of Slugger's post on Motor Oil. If I'm wrong......may he come along and correct me.

 

02-11-2009 09:22 PM	Quote Reply Alert
brye1 wrote: I'm pondering what Brand and type of Motor Oil to use with two vehicles coming due for a change. First is a truck with 80,000 and the second is a Buick with close to 30,000. Synthetic??? Yes/No....Why???? I know we disscused Oil Filters but after a Search I found no post covering the pro's and con's of Oil Brands and Types. "OLDMAN" from central Michigan in the little town of Owosso. 48867 Oldman and others, I've researched both conventional 'Dino' oils and synthetic oils for several years now. I don't have access right now to my 'old' computer where most of my 'research links' exist at this time. I'll access it later to find a few of them. Here are a few interesting links I just found for your info and knowledge: Synthetic Oil Explained (Sept 2004) Synthetic Oil Technology (2007) Synthetic Oil Life Study (2002-2005) Synlube - Lube 4 Life (Click on other 'Dashboard' titles for added info.) FAQs - Synthetic Oil Synthetic Oil Myths Valvoline - Synthetic Oil Wayne's Garage on Synthetic Oil (Read other menu titles too.) And for Gardenman: Alpar.com on Synthetic Oil I'll post my own personal experiences with both non-synthetic 'Dino' oils and synthetics over my 50+ years of automotive work and racing experiences later. I will say that 'Synthetic Oil' DOES NOT CAUSE LEAKS..... it only exposes leaks that were ALREADY PRESENT, but often clogged with 'sludge' from previous conventional oil 'neglected maintenance'. My own experiences with syn oils HAVE ALL BEEN FAVORABLE. Slug-Gunner Keep an "Open Mind" - You'll NEVER STOP LEARNING!
Slug-Gunner - - - Augusta, GA - - - Keep an "Open Mind" = You'll NEVER STOP LEARNING!

 

Things to look at.

 I started this at 75,000 miles....

 Felt a difference with in minutes of driving.

 Have a program that will tag a 300,000 guarantee on your motor........................




Sold by Sears

Scooter:
I just bought two 5qt, jugs of this same oil. I plan on using it in my 1978 Chev. 350 V8 PU with 78,000 actual mi. and my 1993 Pontiac. Gran Prix with 142,000 actual mi. on that one. I'm happy to hear good reviews on this product. Thanks.

Posted By dinoboy@xplornet.com on 06-25-2011 10:10 AM
I just changed the oil in my '97 GMC half ton yesterday. It takes five litres (quarts?) and I found a 5 litre container at my local big box...nice! It wasn't until afterwards that I noticed it's 5-20 wt, not the 5-30 I usually use. Summer temperatures here usually range from 75-95 F (20's-30's C). Do I need to change my oil again?

Some of the newer 'Hi-Tech' engines call for 5W-20 oil due to the 'tighter engine tolerances' and also for 'eco' (higher gas mileage) reasons.  Use the oil that is recommended by your owner's manual for your engine, unless it is 'high-mileage' and has shown signs of 'oil consumption' recently.... if so, then a higher rating oil might be beneficial.  The type of driving you do can also determine the best weight oil you should be using too.  City and stop-and-go driving puts your engine under more stress and usually HIGHER ENGINE AND OIL TEMPS than highway cruising speeds do and I'd recommend either a synthetic oil or syn-blend oil be used under those driving conditions.  I run FULL SYNTHETIC in all my vehicles and every one of them, except my NEW 2011 Nissan Frontier PRO-4X, has over 300,000 miles on them - without any oil-related engine problems to date.

One question that I have is, "What does it look like inside your valve cover opening under the oil filler cap?"

If you have a 'HEAVY SLUDGE' build-up, then your engines oil passages are getting 'clogged-up' and restricting oil flow somewhat.  If so, then you need to use a 'high-detergent' oil like Pennzoil or a high-detergent additive like "Risolene" to clean out some of that sludge and build-up in the oil passages.  This will also clean deposits out of hydraulic lifters and eliminate a lot of 'tappet noise' on cold engine start-ups too.

I'll try to locate some of my older postings on both oil and oil filters and update them for our members.  There is a lot of useful and informative web sites out there for those who want to me MORE KNOWLEDGEABLE about modern lubrication products.  A lot of improvements and changes have been made since the oils our fathers used and in our 'youth' for some of us 'old geezers'.  LOL

BTW:
If you decide to replace your 5W-20 oil with 5W-30, then you can SAVE YOUR 5W-20 oil in the container it came in and use it for 'top-off' oil between oil changes.  The small difference in 'oil weight' will not make a difference under those conditions.... and you won't have thrown money away by making the change now.  It would also make an IDEAL general lubrication oil for general use around the house too by putting some in one of those 'oil squirt cans'.

Posted By Oldman on 06-27-2011 09:15 AM
Scooter:
I just bought two 5qt, jugs of this same oil. I plan on using it in my 1978 Chev. 350 V8 PU with 78,000 actual mi. and my 1993 Pontiac. Gran Prix with 142,000 actual mi. on that one. I'm happy to hear good reviews on this product. Thanks.

Let us know if you feel a difference...........Check the capacity......Mine"302"is 5qts 6 with a filter change.