duffsr

$.02 Just mind the short trips in combination with hard driving. This is the UOA from my car with 11 months and 3,400 miles of severe schedule driving. The oil was testing in the 5w-20 range and i had abnormal bearing wear.
https://www.s2ki.com/s2000/topic/898...#entry20991198

BirdShot

Like I said within that thread, I don't necessarily believe your copper values automatically mean bearings. Read further into the thread to see my opinion. Test your fuel by GC and I would be willing to bet you would see that fuel dilution is what caused your viscosity loss, not shearing.

Short trips and autocross will be harder on your engine and the potential for fuel dilution will be even higher.

rob-2

so with 0w-30 the oil will thin out and cause bearing damage?
[/quote]

Yes and no. What happens with all oils is they thin with use/age. Fuel, heat or just break down over time. Consider that most oils will start off a 30 and get closer to a 20 about the time of a change. The oil, acts as the buffer between your bearings, as they're not ball bearings. A good quality oil ensures that the two pieces of metal never really touch and are constantly suspended between oil. As the oil thins this protect decreases. It's not to say a 40 will cause no bearing wear and a 30 will. The reality is the difference between a 5w30 and a 5w40 in real world terms is +/- 1-5% protection. However if you factor in your driving conditions, use and motor this may or may not make much of a difference for you.

The ONLY reason I run a 10w40 or 5w40 is because we see many days above 100f+ and I know that my oil gets really hot. I also know that spending a lot of time WOT 6k+ rpm is tough on the motor. The hotter it gets the more it thins with time. In a lab test you might see the 5w40 gets you 5% more engine life than a 5w30 under these conditions, but a national sample may see motor failures for non-oil related issues prior to the failure rate caused by the oil.

IE oil difference failure range 270-285k, and average motor failure 220K. In this hypothetical example, the quality of the oil would have an impact on the life of the motor but only after all other factors were dealt with.

It's rather like people debating how getting gas in the morning means you buy more gas for your $. While it's true that temperature makes a difference on the volume of gas, it's about 1% while driving style has a far greater impact. And the reality is that gas is stored below ground and less affected by air temp than most people understand. So while the statement has some truth and can be proved in the lab, showing volume differences it ends up being moot.

It's why I find these types of debates or discussions to be so silly. It's bordering on the ridiculous. Honda spec's their motors with the oil that provides it enough protection to run for hundreds of thousands of miles. They were slow to move to 5w20 until oil companies improved the quality of motor oil. We have a family Honda that just ticked over 100K and runs a 5w20. Burns a tad bit of oil, 1qt per 5k which is acceptable. If we switch to a 5w30 it burns no oil.

rob-2

Like I said within that thread, I don't necessarily believe your copper values automatically mean bearings. Read further into the thread to see my opinion. Test your fuel by GC and I would be willing to bet you would see that fuel dilution is what caused your viscosity loss, not shearing.

Short trips and autocross will be harder on your engine and the potential for fuel dilution will be even higher.
[/quote]

Agreed but even this is very easy on a motor. I've never seen any sizable effects of short distances and autocross. I change my oil 7-10K.

The only place you're going to see problems is at the track where high heat and long WOT sections put lots of stress on parts and oil. Autox is short bursts. Short trips lead to moisture in the oil. Still with modern oils it's hard to show any affects that will lead to a greater than mean average failure rate.

BirdShot

Sorry, but this is mis-leading. Under normal conditions, engine oils will THICKEN over time/use. Lubricating oils in most applications will ALWAYS thicken over time unless exposed to outside contamination. This is primarily due to depletion of reserve alkalinity, increase in acidic contamination resulting in oxidation of the oil. The shearing effect of modern oil formulations is minor. FUEL contamination is the primary reason you are losing viscosity and I will have to beat this drum even louder and say that the lab that is primarily used by members on this site DOES NOT HAVE ACCURATE FUEL PERCENTAGE DETECTION!

BirdShot

Autocross is hard on a motor oil/engines. Extreme heat and stress, then cool down. Extreme heat and stress, then cool down. Extreme heat and stress, then cool down.

Moisture in oil can lead to accelerated oxidation, but it is quickly burned off at once operating temp is reached. This is not typically an issue for engines.

I would argue that an engine running at operating temp, at WOT, in a track day session will see less wear than an engine that see's short trips of start up, short run then shut down, then repeat.

SpitfireS

With the word protection you are still saying & thinking a 40 weight is better.
Yes, a 40 weight will have a higher HTHS but it doesn't mean its better in the F20/F22.
It depends on how much HTHS your engine needs.
If the minimum HTHS requirement is (lets say) 2.0, a 3.2 oil will do as well as a 3.7 or 4.2 oil in protecting, keeping parts apart, etc.
The down side of thicker oil is that there will be less flowing through the engine at WOT.

Do you have an oil temp gauge?
You're so sure your oil gets really hot at 100F days.

IIRC there is a Youtube video of a Civic and an S2000 (and others) on a track in Japan to test OEM cars using OEM parts being able to go fast for more than just 1 lap.
Among others they mentioned the oil they used for that track event and had to slow down when the engine was getting too hot.
There was a red warning light in the cabin to show the drivers to slow down.
The Civic with a 30 weight had less engine temp issues and could run fast longer!
This showed the thinner oil will keep the engine cooler even during track loads, revs and temps.

It goes without saying one should not go (much) thinner than the manufacturer recommends.
In our case with the F20/F22 it is a 30 weight.

Thicker is nothing more than thicker, not better

rob-2

We're not in disagreement. I started off with 'fuel' as the leading cause for oil degradation. Oils also break down over time and are less effective.

rob-2

If the term protection is misleading, sorry, it's the thicker properties that provide more 'bumper' between bearings. As I stated before I believe the difference between weights to be <%5.

I know my oil thins with lower grade oils and 5w30. On cold start up, no TCT noise, driving the snot out of it in 100f days for a few hours and I get home with tct noise. Car cools down, starts back up without noise. Switch to a 10w40 and this never happens.

Since my TCT hasn't failed and it seemingly repairs itself with cool oil AND the switch to a 40 weight out resolves this problem I believe this is enough proof for me to run the thicker oil. I'm not saying everyone should be driving 40 weight, like you're saying people should stick with 30 weight.

Further to the point about high heat and 40 weight. Our subi strongly recommends 10w40 for their cars driven in 100f+ days and says it's the oil for -4f to 100f+, run 5w30 for -20f to 100f. Anything past 100f and they want a thicker weight oil. If memory serves me I believe in the middle east Honda will put 10w40 in the S2000 as standard practice. Correct me if I'm wrong.

This all said. I think the difference between the two weights is mostly personal choice. I switched because of the TCT and the 'feeling' that the oil is better suited for my climate. I won't be equiping my car with temp and pressure gauges to prove this is a better match for me.

Most of the evidence provided in this thread is theoretical at best. There is no science behind it. Show us tests of motors failing early do to bad oil and I'll show you low weight, high stress motors driven on crappy oil. The leading cause of early motor failure is not bad oil, it's user error and part failure.

rob-2

Would love to see some real world tests on this. WOT has everything running at max output. Typically this is where things fail early. A quick review of your theory would see race cars out lasting Toyota Camry sedans. Since this is not the case I suspect testing will show this theory to be wrong.

Re-autox: things don't actually get that hot. It's mostly 1st to 2nd and a lot of second gear for 30-60seconds. Than a pause idling for 5-10 minutes. Autox likely best simulates LA traffic where people race between lights and idle. I'm not aware of LA cars having higher failure rates that other parts of the country.