Never using a 40wt oil again!!

[OVERKILL]

Originally Posted by jbutch
Originally Posted by Gokhan
Originally Posted by OVERKILL
I wasn't stating that the 15% figure was accurate, simply that, without shear, that's how much fuel would be required to achieve that much visc loss.

...

Curious as to where this 25% figure comes from?

I hear you.

I was looking at the paper I linked in my previous post.

I still suspect a lot of permanent oil shear in jbutch's engine. Regarding fuel dilution, I would drive for about 25 miles on the freeway before I sample for the UOA, which should take care of most of the fuel dilution so that I can see how bad the permanent oil shear or oil thickening due to oil oxidation is without worrying about the fuel in the oil.



Really interesting reading the replies in this thread even though I feel like I highjacked the thread, haha.

A few precisions, before sampling any oil to be sent to a lab, I always drive 20-25 minutes while the oil is at 90c-100c to try to clear out any excess fuel.

Also in all my OCIs, the oil has never move a millimeter up or down on the dipstick and I check it very often. Also, everytime I change the oil, it does not particularly smell like gasoline (this is very subjective though).

Curent fill is Rotella MV 5w30, an SN rated HDEO, this will be my first UOA with a non-RC (GF5) oil.

I'd like to send it to BS (to keep the trend) and mayne OAI, but its getting more expensive to do used oil analysis than actual oil changes...

I think you really do need to send it to a lab (to reiterate what I said above) that actually tests for fuel, even if it is only once. Would be interesting for sure to see what Blackstone shows for Flashpoint compared to what the other lab shows for fuel. If you looked at the thread I linked, Blackstone showed <0.5% fuel, whilst GC showed 3%. And that was with a far higher flashpoint than what you've been getting on your reports. I'm definitely curious.

 

[Gokhan]

Try running the Amsoil ACD SAE 10w30/SAE 30 during the summertime. It does not use any VII -- it's a monograde that behaves like a 10w30 multigrade because of its PAO/POE base oil. There wouldn't be any oil shear because there is no VII (light PAO base stocks shouldn't shear significantly) and you can then see how much the fuel dilution decreases the viscosity.

Another oil with almost no VII is the Valvoline Advanced Synthetic 5W-20. You can give the Valvoline Advanced Synthetic 5W-20 a try in the wintertime to see if it outperforms in viscosity the 5w30 oils you use.

 

[UNC151]

Originally Posted by jbutch
I'd like to send it to BS (to keep the trend) and mayne OAI, but its getting more expensive to do used oil analysis than actual oil changes...
If you are concerned about fuel dilution, you need a lab that uses gas chromatography to determine fuel dilution. Blackstone is not that lab. Look to OAI or Polaris ($19.50 via Amsoil) and it includes TBN. Otherwise, lower your OCI and stop testing.

 

[jbutch]

All right, next uoa will be through OAI, they have a lab in Edmondton. Will post in the appropriate section when it will be done. Could be a while, I only have 2500kms on this oil.

 

[yowps3]

Originally Posted by OVERKILL
Originally Posted by yowps3
I wonder why Europeans recommend 40 wts while American and Japanese are recommending thinner and thinner grades.
Especially on today's motors that are ultra hard on oil


My SRT calls for a 0w-40, as does the Corvette now. You'll find that most Hi-Po mills call for heavier oils and 0w-40, with its wide spread, is probably the most common flavour. This aligns with the expectation that these applications will encounter situations where oil temperatures are elevated (track days for example) and the additional protection is needed. This runs contrary to the expectations for most "appliance" applications where runs to Walmart and the Beer Store or loafing down the highway are not going to elevate oil temperatures. These are also the bulk of sales, so tiny incremental gains in fuel economy realized through the spec'ing of lighter oils have a cumulative effect on CAFE credits.

To ensure that the lighter oils will work suitably in these applications you'll typically find one or more safety mechanisms in place designed to keep oil temperature within an appropriate range and, if that cannot be done, reduce output:
- Oil coolers
- Increased sump size
- Finned oil pans
- Thermal castration mechanisms (PCM pulls power when oil temperature hits a threshold)
The 1.6 T-GDI Kia has a beefy oil cooler mounted right on top of the monstrous oil filter, a large 4.5L oil capacity, extensive ECU thermal management program and even piston oil jets

Talk about overkill for a 1.6 - but understanbly so as it is very crammed and reaches operating temps unbelievably quickly