5w20 in an 08 Buick LaCross 3.8 (5w30 standard)

[Owen Lucas]

Using Amazon Basics High Mileage Synthetic Blend.

Would there be any drawbacks?

Engine has 120k on it.

 

[wpod]

Because ?

 

[B1974]

I would use a 5w30 blend or full synthetic for this car and not a 5w20, as it's a thin weight oil and not meant for this car.

 

[Slick3914]

Run it till she blows!

 

[demarpaint]

I'd use 5W30 in it.

 

[kschachn]

Using Amazon Basics High Mileage Synthetic Blend.

Would there be any drawbacks?

Engine has 120k on it.

Are you that desperate for a tiny fuel economy increase?

 

[Brian123]

Using Amazon Basics High Mileage Synthetic Blend.

Would there be any drawbacks?

Engine has 120k on it.

Don't know, you can always use it and report back. I know there is 1 member here who would think it is a great idea, of course he might also tell you 2 go Thinner.

 

[Eddie]

No upside and possibly a real downside. JMO. Ed

 

[oggb]

Would there be any drawbacks?

It'll ruin your reputation on Bob Is The Oil Guy, but A.E. Haas might adopt you and let you drive his Ferrari

 

[Trav]

Using Amazon Basics High Mileage Synthetic Blend.

Would there be any drawbacks?

Engine has 120k on it.

This old lump was not designed to run on thin oils, many of the Gen II of these engine spec'd 10w30, the 5w30 was an EPA thing in these engines.
I had one and did a UOA with Mobil 1 0w40 which showed low wear, after doing a preemptive LIM gasket swap I used a low viscosity 5w30 in it and did a UOA to check for coolant ingress, the wear metals were way high. After switching back to 0w40 and the wear decreased to prior levels.

Not scientific but enough for me to avoid lighter oils in these engines, I would run Mobil 1 ESP 5w30, 0w40 or a 10w30 and call it good.

 

[oldhp]

Try 0W16 next. See how much you MPG goes up.

 

[Owen Lucas]

Because ?

I scored 6 jugs of 5w20 on Amazon for $4.60 each incorrectly thinking that was the correct oil for the vehicle.

Are you that desperate for a tiny fuel economy increase?

It's not about fuel economy, just using what I have on hand, which is starting to seem like a bad idea.

 

[dubber09]

You can use it, it's not a very good idea but.
Also, you can mix it with thicker oil to get to approx 5w-30 but you need to do the calcs on what to use and how much. There were tables or formulas someplace iirc.

 

[Brian123]

I scored 6 jugs of 5w20 on Amazon for $4.60 each incorrectly thinking that was the correct oil for the vehicle.

It's not about fuel economy, just using what I have on hand, which is starting to seem like a bad idea.

You scored 6 jugs 4 $4.60 each, so .92 cents a quart, either you got a great deal or you bought some really cheap oil. It would be nice to see a VOA of this oil and maybe after you use it a UOA!

 

[Owen Lucas]

You scored 6 jugs 4 $4.60 each, so .92 cents a quart, either you got a great deal or you bought some really cheap oil. It would be nice to see a VOA of this oil and maybe after you use it a UOA!

There is a thread in the rebates and deals forum that alerted everyone to a massive discount / clearance, maybe even a glitch, on Amazon’s website to these prices.

Many of us bought multiple jugs while the deal lasted for a few days. Those specific item numbers are no longer for sale but their replacement is now 5x much. This is the Amazon basics brand, I think some have commented it’s decent oil.

 

[Brian123]

There is a thread in the rebates and deals forum that alerted everyone to a massive discount / clearance, maybe even a glitch, on Amazon’s website to these prices.

Many of us bought multiple jugs while the deal lasted for a few days. Those specific item numbers are no longer for sale but their replacement is now 5x much. This is the Amazon basics brand, I think some have commented it’s decent oil.

Good Luck with using this oil, my days of chasing the oils like what you bought are over. You get what you pay 4!

 

[StumblingElk]

You would think with all of the analysis and sources cited here we would have more definitive answers by now on things like this.

That said, I would run 5w30 bc that is what is recommended and oil is cheap. Not that I think it really matters but I could certainly be wrong. People here seem to like thicker oils though I'm not sure the data bears that out. Again, I may be wrong.

As an aside,, my Honda has 200k and has had nothing but 5w20 and it runs very well after all these years, abuse, and short trips. I also feed my coyote 5w20 which is heresy according to some. I have even been known to use Fram filters!

Honestly, Im more concerned with using a good oil and mainting a decent OCI.

 

[Owen Lucas]

I ended up buying 5w30. Supertech HM of course.

 

[demarpaint]

I scored 6 jugs of 5w20 on Amazon for $4.60 each incorrectly thinking that was the correct oil for the vehicle.

It's not about fuel economy, just using what I have on hand, which is starting to seem like a bad idea.

You could probably sell it on FB or Craig's list and make a few bucks, then treat the car to a nice 5W30, and sleep easy.

 

[addyguy]

Run it, it will work just fine. Run a 5W-30 for 2-3k, and it will most likely shear down to a high 20-weight, so what is the difference?
It’s been running a sheared-down 20-weight for years!