Why don't you do it right, replace the valve cover gasket and go back to the specified oil? Seems like a logical way of doing it.

 

There is the valvoline high mileage synthetic blend for 23$ would this be better to use and run it to 5k mile oil changes. I cant say how long synthetic blend is to be changed as im assuming 5k miles just as walmarts old synthetic blend jug advertisements. My 99 corvette according to the manual is 7500 miles on full synthetic.
Valvoline High Mileage MaxLife 10W-30 Synthetic Blend Motor Oil 5 QT - Walmart.com

 

Oh no i was simply referring to running different weight oil as well as conventional to synthetic blend. On my 66 fairlane with a 351 cleveland i think i may have ran 10w30 in the winter and 10w40 in the hot texas summers when i was 17 in 2007. I think quaker state conventional oil was around 2.20$ at that time in 2007 a quart.

The question was more about how walmart doesnt stock its 13$ conventional supertech anymore and just this year stopped having there 16$ supertech synthetic blend 5k mile oil so i was forced to the next cheaper option quaker state all mileage conventional for 18$. I still havent done the oil change so i can return the 3k mile oil and swap to a 23$ valvoline synthetic blend if all are 5k mile oil changes that leaves me 2k extra miles without having to change the oil. Its for my younger brothers daily driver 2007 g6 he uses for work. I have a 99 corvette no oil leaks that i run quaker state full synthetic in but on an economy cruiser i dont see a point in running race oil. See my above post about the other option valvoline synthetic blend for 23$ if all synthetic blends are 5k mile oils and not 3k mile as conventional saves me time then doing the oil change sooner.

 

The difference between 10-30 and 10-40 is almost nothing until the weather gets really cold or really hot.

Sometimes I think the engine manufactures decided which oil they recommend by throwing a dart at a wall with little pictures of different grade oils.

Synthetic oil is far superior to conventional oil in every way.

 

The difference between 10-30 and 10-40 is almost nothing until the weather gets really cold or really hot.

Synthetic oil is far superior to conventional oil in every way.

10W-30 and 10W-40 will behave exactly the same when the weather is cold (that's what the 10 indicates) and will only very slightly at high temperatures.

You may have done yourself a slight disservice by using 10W-30 instead of the recommended 5W-30. Newer engines are made to tighter tolerances and the 5W-30 it slightly thinner at startup so provide better lubrication immediately when you start the engine.

 

The 3k on conventional oil is a myth. Pretty much all newer cars can go much longer depending on the type of driving you do. My 2000 buick with 260k on it and my 2009 buick I go by the revolution counter of the computer to change the oil. Never have had a problem. Older carb engines yes to 3k ,but not newer ones.

 

But using a thicker oil or even an oil additive to thwart the inevitable repair needed to stop the leak where the prescribed oil can be used is ludicrous. Fix the car and use the right oil.

That WAS your original question: "Is it okay to switch to a thicker oil 10w40 to help prevent any leaking "

 

I had a guy that dealt in oil a lot tell me that most all engine oil anymore is synthetic to some degree because of the way it is made.

 

Is it okay to switch to a thicker oil 10w40 to help prevent any leaking or is it best to use the 10w30 for bearing clearances.

What does the car's manual say to use? Use that. Unless it's something ridiculous like 0w16. Then I'd think twice.

Even modern conventional oil is much better than oil from decades ago. 3k used to be a thing but now isn't. And, yes, some/many/all(?) "conventional" oil now is a form of synth blend. I've seen a couple people quite upset about that for whatever particular use they wanted full conventional for -- the oil maker changed the formula but didn't put "synth blend" anywhere on the bottle.

If no one wants to change the valve cover for some reason, the best hope you'll have of helping the leak is using the high-mileage oils. They really can work.

 

Oh not necessarily i may have messed up mentioning the leaking part i merely meant switching to a thicker oil from 5w30 or 10w30 to 10w40 for whatever reason higher mileage and such maybe thicker oil. Its almost at 182k so if i use the 4 quarts of the 5 quart jug of conventional quaker state 10w30 i have itll be good to 185k miles.
My brothers 06 saab 9-5 2.3 turbo i like to use full synthetic as the oil flows thru turbo adding heat to the oil i assume.
My 98 z28 ls1 when i was 19-23 in 09-12 i used valvoline full synthetic not sure if 10w30 or 10w40 was along time ago autozone oil and filter special with cam headers 375whp 375 wtq and 501whp 465wtq 6lbs turbo s475 and 9lbs maybe 550whp/500wtq till 169k miles when it threw the stock shortblock wristpin thru the side of the block boosting 9lbs in 4th at the end of the track SAR here in san antonio late 2012 when i was 23 im 33 now.

I had read an article about an ls1 engine and running different oil weights months ago. They had a 300k mile + ls1 engine and ran the same 5w30 for bearing clearance purposes and recommended the same oil versus switching to a thicker oil. Thicker oil would cause more wear on the oil pump or stress the bearings with tighter clearances not sure what all the article contained or how to go about getting 300k+ miles.
That was some of my concern when switching from 30w to 40w.
What are you saying conventional oil is good for mile wise when used on a car thats shifts around 2-3k on an auto?

 

What are you saying conventional oil is good for mile wise when used on a car thats shifts around 2-3k on an auto?

When in doubt, change it at 5k unless there is an obvious reason to change it earlier such as lots of blow-by making the oil look bad prematurely. It could probably be changed later than 5k, but probably a max of 7,500 miles, and cleaner oil is always better than dirty oil, so 5k is a good rule of thumb that makes most people feel good.

Can change it less of course if the car is losing a good bit of oil from a leak since new oil has to be added before oil change time anyway.

For the couple dollars difference, I'd certainly use a labeled synth blend than labeled conventional. Locally, I usually can get synth blend for cheaper than conventional for whatever reason. And I've seen enough synth blend oil wear tests to not worry about needing full synth unless it's for atypical use.

 

there is never any reason to deviate from what the manufacturer recommends,

your oil pump is designed to pump the viscosity of the recommended oil,

when it has to pump a thicker oil, it put more strain on it,

also, a thicker oil is not going to leak any less, or any more

i used to work at a shop, when a customer asked me "what grade of oil should i use?"

i used to answer "what does it say on your oil cap?"

 

Now about this thicker oil debate say 30w-40w im sure bearings do show a little wear above 150k miles or atleast normally you can see the first layer worn off this wouldnt possibly require the use of possibly a slightly thicker oil or are you referring to smaller oil orifices and oil paths requiring the 5w vs 10w.

 

Yeah i see i may have mentioned it wrong i was simply referring to 182k mile car and possibly 10w40 vs 10w30 for possible bearing wear and such. Hot temperatures in texas summer 107 degrees and coldest it gets in winter is 30 degrees.

 

Now this is terrible autozone has the same oil for 26$ vs walmarts 17.97 quaker state all mileage. Autozone has this all mileage quaker state listed as a synthetic blend is this a misreading or false advertisement or is this oil a synthetic blend that can be run up to 5k miles vs the standard 3k mile conventional oil.
Guess walmart is cheaper by 8$ for the 5 quart jug and possibly a synthetic blend which is usually run up to 5k miles.

Quaker State All Mileage Engine Oil Synthetic Blend 5W-30 5 Quart (autozone.com)

Quaker State 5W-30 All Mileage Motor Oil, 5 Quart - Walmart.com

 

There is a difference between a synthetic oil (100% synthetic) and a synthetic blend (A mix between synthetic and mineral oil).

Autozone has it right, the Quaker State All Mileage oil is a synthetic blend.

 

Hey yes im aware of full synthetic, synthetic blend differences and just what is called conventional oil. Thanks for the confirmation.


So its safe to assume this qauker state all mileage is a nice synthetic blend that can be run up to 5k miles? Or is can it be run higher mileage 6-7k? I may just return or swap this 10w30 ive been using for the 5w30 to walmart though ive been using 10w30 the last 30k miles on the car because of the texas heat. Only thing that caught my eye is i was changing the 06 saab 9-5 turbo oil and seen it was 5w30 so went specifically with a full synthetic 5w30 supertech 10k mile oil last year when i was changing the oil on that car as the oil is also run thru the turbo oil feed/drain extra added heat protection from full synthetic. Really am trying to make sure to get the most mileage out of these engines as i was disfigured in a car wreck in 2017 age 27 after someone had rear ended my 2001 ford escort so im somewhat disabled why i prefer doing less oil changes and get the expected mileage out of the oil its a real pain for me. Im somewhat mechanically inclined at age 17 but after having been disabled from that car wreck left me paralyzed a bunch of slipped disc and permanent spine ribcage pain.

 

Oil viscosity will never solve the oil leaking problem on a 15 year old engine so replace cover gasket then determine if the crankcase vacuum is correct .

 

I have a hard time following the OP's posts - too much irrelevant data and irrelevant other vehicles. I don't really have a position on conventional vs. synthetic oil; I've always used conventional in my vehicles (except my newer Honda which calls for 0wxx) and changed it and the filter per the book if not sooner.

If the goal is keep an old blister running as long as possible, don't make your decision based on price. At best you are saving a handful of dollars per change.

 

Ah here it says my g6 owners manual use 5w30 or 0w30 if -20f degrees. Do not use thicker oils 20w50. Doesnt mention anything about 10w30 or 10w40.

Here on ls1 v8 says 5w30 above 0 10w30 can be used for 99 corvette or camaro ls1 5.7 im hoping when i did the last oil change i did use 10w30 full synthetic quakerstate after the cam swap last march. Im pretty sure i didnt select 10w40 as the car has 94k miles pretty low mileage. I think i did go with 10w30 vs the oil caps 5w30 but it never gets below 0 here in texas coldest is 20f degrees in the winter rarely.

SAE30 can be used. I still think itd be fine to run the 10w30 opposed to the 5w30. 5w30 or 0w30 is in reference to -20-0f 10w30 is recommended around 40f or above.

just make sure not to sae50 or 20w50 it.

The thinner oil less friction more power.

 

Do not use thicker oils 20w50. Doesnt mention anything about 10w30 or 10w40.

That's about the (I can't think of a word) comment of the day. It says "Do not use thicker oil" Gee, what do you need?

SAE30 can be used

No it can't. SAE 30 is a non detergent oil and will kill your engine.

 

I still think in 80 degree heat 10w30 would work fine lol.

 

if you think you are smarter than the engineers who designed the engine, then use whatever you want

 

Man here is my proof is 0w30 not SAE30? I may be mistaken not sure what sae means straight 30 weight no with a 0?
5w30 or 0w30 0 degrees or below. 5w30 for 0 and above this is the g6 manual not the 20w50 or higher viscocitys.

Use only 5w30 synthetic oil below 0-20 degrees or 0w30 for extra added lubrication. May i ask is there a 0w30 or is sae30 which i always thought meant straight 30weight meant simply 30weight oil.

Is the sae 30 or sae50 simply a 30w30 and 50w50 on cold starts?
Read the second paragraph about 0w30. 0w30 means theres nothing if you ask me for the first start as in 0 viscosity? Depends i dont know specific oil grade scales when it comes to 0 viscosity.

 

I was using 10w30 the last 20k miles its 107 degrees here in summer texas heat. Im going to return the quaker state 10w30 in favor for a 5w30 i hope they have one on the shelf. A guy over on the g6 forum has 266k miles on his 06 g6 v6 3.5l im hoping to get the same mileage. The 2007 g6 isnt driven hard its my younger brothers daily driver for work i just do that mechanics to it. That little article from the owners manual in the glove box should give all the information needed.

I probably do need to figure out how to do a transmission fluid change on this car as its at 182k. Im hoping there a bolt drain plug would be nice to change the auto trans filter to get the most life out of the transmission.

 

Im all for a good oil discussion but youre tearing into a lawnmower at this point.

 

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In October 1954, three businessmen with a mere $3,000 in start-up capital introduced the first STP® product in St. Joseph, MO. STP®, began with one product — STP® Oil Treatment. It helped automobile motor oil resist thinning at high temperatures and pressures. Our history – a timeline 1954...

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A simple google of... What does SAE stand for?
Answer... Society of Automotive Engineers

SAE30 = straight 30 weight oil.
xxWyy oil = detergent oil. It also has additives to reduce friction at start up in cold weather (the xx).

Older engines leak. I, personally, would not use synthetic in a used engine unless it had synthetic from day-1.

Back in the day, dunno if it still applies, Pennzoil had a wax substance within the refined oil.

I always use mfg recommendation on what weight oil to use cuz they have spent tons-o-dollars on research.

FWIW.... I knew a lady who drove a Cadillac close to 100K miles. Wondered why her car would not start one very cold day. Come to find, she had never changed the oil....believe it or not.

It's your toy. Play with it how you want....Don.

 

Older engines leak. I, personally, would not use synthetic in a used engine unless it had synthetic from day-1.

I had toyed with the idea on my 2001 Cummins, but at 561,000 miles, and it ain't broke, don't fix it.

 

Yeah i bet i use to use the 10w30 10w40 quaker state in my 66 fairlane 351cleveland 4v 9" with 4.10s 4 speed toploader when i was 17 in high school class of 2007.
I since bought a 95 z28 6 speed at 18 not sure what oil i used there but purchased a 98 z28 hardtop 6 speed with 119k miles for 3800$ with ttl from a small car lot. Its was in great condition bone stock. I used autozones valvoline i believe full synthetic 10w30 which is recommended for 0-40f above in the ls1 5.7 manual. Made 375whp 375wtq smaller cam then the corvette, headers and ud pulley. I later thru a s475 borg warner 1.32 ar turbo on it made 501whp 465wtq at 6lbs and possibly 550whp 500wtq 9lbs. Ran 126mph-131mph 128-129mph in 30-40 degrees midnite weather at san antonio raceway. Didnt use slicks or drag radials so the 60fts were slow 2.2. That was from 2009-2013 when i was 19-23. Im 33 now and suffered severe body damage from the idiot that ran into the back of my 2001 escort daily driver.

 

well swapped the 10w30 for the 5w30 problem solved 5 minute trip up to walmart.