Today's viscosity experiment

[widman]

It took a while for me to convince the Kia distributors to move down from 15w40. Finally them moved down to 10W-40, but were having trouble with click-clack engine noises, making them sound more like diesels. They wanted to go back to 15w40 for all.

So today I finally got my chance. They took three identical cars with less than 3000 miles on them (2.4 engine) (all in for their first service) that sounded terrible and put 15w40 in one, quieting it slightly.

So I put 5w30 in one and 5W-20 in the third. (ambient temps were 85F, but we let them all warm up anyway)

The 5W-20 quieted down to what the 15w40 sounded like, but the 5w30 became super quiet. So I drained the 5W-20 and put 5w30 in that one too. Total quiet. When we closed the hood the mechanic thought the engine had shut off.

The 5W-20, 5w30 and 10W-40 are all identical formula SN oils. The 15w40 was CI-4.

 

[randomhero439]

WOW

Just one more reason to not trust dealerships

 

[Stelth]

Originally Posted By: randomhero439
WOW

Just one more reason to not trust dealerships

 

[Art_Vandelay]

What's the owner's manual recommend in your country?

 

[friendly_jacek]

So, 10W40 was the noisiest, 5W20 and 15W40 were somewhat noisy, and 5W30 was the least noisy?

All had hot engines?

How do you explain that?

 

[Art_Vandelay]

Originally Posted By: friendly_jacek
So, 10W40 was the noisiest, 5W20 and 15W40 were somewhat noisy, and 5W30 was the least noisy?

All had hot engines?

How do you explain that?


I'd love to know myself. At that ambient temperature it should be impossible for any one of those oil weights to make a brand new engine sound terrible.

 

[Gabe]

My Sable sounds better on 30 wt than 20.

 

[KCJeep]

Interesting!

 

[uart]

Assuming that the differences were not just imagined, then it's probably a compromise between noises arising in different parts of the engine. A thinner oil may be giving better flow and quieter operation in some part of the engine and a thicker oil giving better damping and quieter operation somewhere else.

So perhaps in this case 5W30 just happened to be the best compromise between the two.

 

[widman]

Noises were quite similar in nature, just louder. Sounded like a diesel or sewing machine. All tests on 3rd floor of dealer in quiet part of shop with cars within 10 feet of each other.

Here is the owner's manual. I also have a Kia service bulletin that recommends 5W-20 in all but tropical climates and 5w30 in tropical areas.

 

[KCJeep]

I'd rather run 5w30 in our new KIA as well, but of course here in NA I'm under warranty threats if I do. So the thickest 5w20's I can find will have to do.

 

[Clevy]

Originally Posted By: KCJeep
I'd rather run 5w30 in our new KIA as well, but of course here in NA I'm under warranty threats if I do. So the thickest 5w20's I can find will have to do.

What do they recommend in Europe? If the Europeans can run a 30 grade it's absurd that you can't however if they are consistent overseas as here then it could be that a 20 grade is ideal and not just adequate

 

[mechtech2]

OK. It is quieter.
But is there loss of protection or other downsides?

 

[widman]

Noise means something is hitting or rubbing. Without offering any technical proof, I's say that less noise is less hitting or rubbing, therefore more protection.

 

[Clevy]

Well less noise tells me thicker oil film however does the oil film need to be thicker,or is a thinner film still equate to equal wear rates?

 

[uart]

Originally Posted By: Clevy
Originally Posted By: KCJeep
I'd rather run 5w30 in our new KIA as well, but of course here in NA I'm under warranty threats if I do. So the thickest 5w20's I can find will have to do.

What do they recommend in Europe? If the Europeans can run a 30 grade it's absurd that you can't however if they are consistent overseas as here then it could be that a 20 grade is ideal and not just adequate


Don't know about all of Europe, but "lube guides" from Castrol and Shell and Valvoline in the UK recommend 5W30 or 5W40 for most current model Kia's. Similar story in here in Australia with mostly 5W30 recommended, sometimes with a secondary option of either 10W30 or 10W40.

 

[Clevy]

Originally Posted By: uart
Originally Posted By: Clevy
Originally Posted By: KCJeep
I'd rather run 5w30 in our new KIA as well, but of course here in NA I'm under warranty threats if I do. So the thickest 5w20's I can find will have to do.

What do they recommend in Europe? If the Europeans can run a 30 grade it's absurd that you can't however if they are consistent overseas as here then it could be that a 20 grade is ideal and not just adequate


Don't know about all of Europe, but "lube guides" from Castrol and Shell and Valvoline in the UK recommend 5W30 or 5W40 for most current model Kia's. Similar story in here in Australia with mostly 5W30 recommended, sometimes with a secondary option of either 10W30 or 10W40.


That's utter bull. If they can use those oils there then the consumer here shouldn't be threatened with denial of warrantee for wanting to use one of those grades. If its acceptable somewhere else then it should be acceptable here as well.
Even if a consumer decided to stick with a 20 grade,they should at least have the option.

 

[uart]

Originally Posted By: Clevy
If they can use those oils there then the consumer here shouldn't be threatened with denial of warrantee for wanting to use one of those grades. If its acceptable somewhere else then it should be acceptable here as well.

Yes it seems strange. Perhaps they're worried that if their fuel economy figures are all based on xW20, but not everyone is using xw20, then some of their CAFE credits might be in jeopardy?

Every car I've ever owned here came with a chart of available viscosity choices similar to the one the OP posted previously. With the understanding that if you're in one of the colder parts of the country that you'd take one of the thinner choices, and if you're in a hotter part or doing lots of towing in hot conditions then you can take a heavier option.

Originally Posted By: widman

BTW widman, I'm trying to read the footnotes but don't speak Spanish. Does footnote *2 say "In the Middle East, don't use 5W20"?

 

[Doug Hillary]

Hi,
widman - What engine designation is this?

 

[widman]

Quote:
BTW widman, I'm trying to read the footnotes but don't speak Spanish. Does footnote *2 say "In the Middle East, don't use 5W20"?


Yes.

Quote:
Hi,
widman - What engine designation is this?


2400cc

In a few days I should have feedback on how well it does the same in the 3 cylinders.

Quote:
Every car I've ever owned here came with a chart of available viscosity choices similar to the one the OP posted previously. With the understanding that if you're in one of the colder parts of the country that you'd take one of the thinner choices, and if you're in a hotter part or doing lots of towing in hot conditions then you can take a heavier option.


The problem with that chart is that people assume that it gives the same results. Here we are in the tropics. we get a dozen nights a year where the night-time temp drops below 65F, but not normally below 72 in the morning. So the noises and other problems develop.