mobil 1 oil weights (weirdnesses?)

[slugsgomoo]

Let me start by saying that I realize that this is weird, but this happens in *both* of my cars, and i'm not sure why, perhaps they're picky-

Generally speaking around 2700 miles into an oil change, I can tell that the car *wants* new oil, without looking at the sticker. It proceeds to get more noticeable (and annoying) until i change it, and then it's a brand new car for the next 2500 miles.

the details:

2.0L Turbo Mitsubishi (4G63t) running some decent boost (15-17psi). normal street driving doesn't see the motor spin too fast, but I *do* spin to 7k+ (occasionally bouncing off the (modified) limiter @ 8k).

Currently, I've been running mobil1 15w-50, but this heavier oil seems to exaggerate the "end of life" symptoms of the oil more than the 10w30 m1 that i've always run in the other car.

Does it make sense to switch back to 10w30? That's what i've been planning on, since i'm not exactly beating the car on a track every weekend, especially with the season ending here in a few weeks.

I always use M1 in the motor with a napa gold filter, for what it's worth. I'm not averse to spending money on fluids (all of my diffs, t-case & gearbox run Redline)- I just want to keep the protection, while eliminating some annoying issues (phantom knock, slow spool up, etc).

Am I headed down the path of logic?

 

[Pablo]

What does a UOA tell you?

 

[TomJones76]

How does your car tell you that it wants new oil?
Do you take this car to the track?
If so, what events, and what duration, both in time and miles?

 

[Leo]

Whats the mileage of your motor?

 

[Shannow]

I noticed something on my 4Runner.

I keep fuel economy records (well used to until it became the second car).

Change the oil (M1), drive it, and at around 12,000km, the economy dropped off. 3 tank fulls of depressed economy, and I'd change it.

Economy would return for another 12,00km or so.

 

[Sid]

Is your oil dark? I know they say this doesn't indicate anything but on my old the car the oil would get very dark soon and would sort of thicken up. And the motor would feel good for about 2000 miles and slowly start feeling sluggish from their on out. I wasn't sure why the oil would get dark though. The engine only had 50K miles on it but it was over 12 years old.

 

[slugsgomoo]

it's got 124,000 miles on it, and the oil gets a bit darker towards the end.

I use an OBD-I logger on my palm pilot, and my car has a "phantom knock" in low throttle around 1500-1800 rpm that is basically the ECU freaking out. However, once it gets to about 2700 miles, it gets REALLY noticeable- to the point where you will carry it over and the computer will pull the timing. Before you ask, no it's not real knock (out of boost) and this is a pretty normal, yet irritating symptom of the 4g63. I have a new EPROM coming for the car that ignores knock outside of boost.

TomJones: i haven't gotten to take the car to the track this season, as i've only had it a couple months and have been trying to sort out some issues. I would say that the car definitely see's some dragstrip style abuse however. It's hard to get any kind of real tuning done without doing 2nd & 3rd gear pulls up until 7500-8k.

Pablo: I haven't done a UOA because I am not that 1337. If you have a simple, easy way (cheap) to go about it, let me know and I will give it a shot.

 

[kang]

quote:

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Originally posted by slugsgomoo:

I use an OBD-I logger on my palm pilot,

---

Sorry to change the subject, but can you tell me about this? It's just what I need... I've looked and never found anything that looked good/priced right, etc.

Thanks.

 

[lilslyk]

quote:

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Originally posted by slugsgomoo:
Before you ask, no it's not real knock (out of boost)

---

Can you please explain your "out of boost" statement?

The reason I bring it up is that I want to make sure you realize that "knocking" is not your car "running out of boost," but rather it is the fuel in the cylinder mixing with the air and igniting BEFORE the spark from the plug, therefore causing the combustion to force against the piston as it is still in the up stroke, causing a "knock"

I believe when you say "running out of boost" you actually mean that the flowrate of the air becomes too great for the intercooler and it cannot keep it at a low enough temperature, therefore creating a fuel-rich combustion environment which leads to "knocking" as described above.

What octane gas do you use? As I'm sure you know higher octane gas will alleviate most knocking issues under high boost. The "fantom knock" you describe could be from the lifters (are you getting lifter tick? I know I did in my 4g63..) in which case a thinner oil could help you out there.

 

[lilslyk]

quote:

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Originally posted by kang:

quote:

---

Originally posted by slugsgomoo:

I use an OBD-I logger on my palm pilot,

---

Sorry to change the subject, but can you tell me about this? It's just what I need... I've looked and never found anything that looked good/priced right, etc.

Thanks.

---

Try http://www.pocketlogger.com

What is your car, year and make? I have my OBD-I cable and software for my palm from my '91 eagle talon still laying around...the stuff is $155 new.

 

[theguru]

Does he mean "Off boost?

Running 15w-50 could increase the spool up time.

A UOA is really the only way to tell if the oil is spent. Visual is not a good indicator. Terry is the man to talk to.

If it was my car I'd probably try the CG 0w30 or Redline 5w30 or 10w-40.

 

[slugsgomoo]

4g63's really don't knock when they're at low TPS and no boost unless you have bad bearings, which is not the case (thankfully). I've also got the upgraded 3rd generation lifters (bigger bore) and the lifter's don't tick (checked w/ stethascope). The ECU on the car is pretty well known to read knock where it isn't actually happening, and usually below 2k rpm. The new Keydiver chip that is going in the car this week actually has a code to ignore any knocksum when the ECU senses that the car is out of boost. Frankly, the only time I really care is when i'm over 30% TPS and building boost.

lilslyk: I use Chevron 92 exclusively, though I'm planning on switching to AVGAS or Sunoco 110 (Standard Leaded) here in a couple months, since I drive the car so infrequently now (cost doesn't make as big of a deal).

when I say "out of boost" I mean that i'm still reading vacuum- i.e. most of the time I get phantom knock, it's 1800rpm, 12" of vacuum and 15% throttle position.

I'm using the MMCD logger software for my car, seeing as that I already had a cable, and the software was free.

Kang: I don't know if there is something available for you- it depends on what kind of car you drive. The software that I use is only applicable to 1989-1994 DSM's running 4g63's.

I will do some searching around here for some topics about UOA.

 

[lilslyk]

quote:

---

Originally posted by slugsgomoo:
4g63's really don't knock when they're at low TPS and no boost unless you have bad bearings, which is not the case (thankfully). I've also got the upgraded 3rd generation lifters (bigger bore) and the lifter's don't tick (checked w/ stethascope). The ECU on the car is pretty well known to read knock where it isn't actually happening, and usually below 2k rpm. The new Keydiver chip that is going in the car this week actually has a code to ignore any knocksum when the ECU senses that the car is out of boost. Frankly, the only time I really care is when i'm over 30% TPS and building boost.

lilslyk: I use Chevron 92 exclusively, though I'm planning on switching to AVGAS or Sunoco 110 (Standard Leaded) here in a couple months, since I drive the car so infrequently now (cost doesn't make as big of a deal).

when I say "out of boost" I mean that i'm still reading vacuum- i.e. most of the time I get phantom knock, it's 1800rpm, 12" of vacuum and 15% throttle position.

I'm using the MMCD logger software for my car, seeing as that I already had a cable, and the software was free.

Kang: I don't know if there is something available for you- it depends on what kind of car you drive. The software that I use is only applicable to 1989-1994 DSM's running 4g63's.

I will do some searching around here for some topics about UOA.

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OK you sound like you know what you're talking about. The "out of boost" comment threw me off and I was thinking you were some ricer with a turbo just so you could say WOOOSHHH and mean it

As I'm sure you know, with the leaded gas...bye bye 02 sensor life!