How did water get in rear axle??? $1,100 ago

[zzman]

I stand corrected, the oil pressure gauge doesn't move up until about 1/2 second when started. (I guess I was seeing things)

But I did notice (when looking harder) as soon as I turn the key on the gauge moves from below the red line (on the peg) to just on top of the red line (no cranking yet). That's weird.

So you guys are saying the gauges are junk? I have always notice the oil pressure dropping (slightly) when engine is real hot, I've noticed that in all my vehicles. I felt that is correct tho, a real hot engine would mean real hot oil, so the thinner it would be, I figured it would lose pressure.

 

[Curious Dave]

You are correct... Oil pressure does drop when the oil is heated up. If the oil is over heated then it fails, and the viscosity is thinner from there on. That means lower oil pressure at startup, as well as lower operating pressure at normal operating temperature. That is how I used to determine if I needed an oil change in my BB Chevy years ago. I never used the 3000 mile rule. If the oil broke down and the pressure was low... change the oil. The oil never did last more than a couple of months in the summer time. It did break down in a week one time though. But it was 600 horses naturally aspirated, and the temp was in the 100's for a week. I still do this with the Cummins. If I see the pressure is heading south I take it in for a change. That or I do go the 3000 miles. It all depends on what I have been using the truck for and what time of year it is. Sometimes if I just drive in the winter I will go the 5000 mile mark. But hauling I always do the 3000 or the pressure drop.

The cold vs. hot oil and viscosity all plays along with the multi-grade oils. Many people think that the first number is for winter and the second number is the weight. That is way wrong.

The first number is the actual weight of the oil (as compared to a single weight), and the second number is the operating charecteristics of the oil at a rated temperature. That means that when the oil gets to a referenced temperature it has the charecteristics of that higher number oil at the same temp. So if you have a 10w/30 you have a 10 weight oil and it functions like a 30 weight at a referenced temp. 10w/40 is a 10 and functions like a 40 at the referenced temp. So on and so on. Unless something has changed in the last 20 years it should be the same scenario.

But as Harvey was suggesting... Factory gauges are not always the best thing out there. I put an entire set of Autometer gauges in my truck. I figured that $1000 in top end gauges and mounts was well worth the cost if I could monitor my drivetrain more effectively and accurately. The factory/aftermarket gauges are not that far off... But at least I have a backup to verify at all times.

 

[steved]

The factory oil pressure gauge is completely FAKE (I will qualify this... all 3rd gen gauges are fake, and any 2nd gen that's been reflashed will be fake)... it uses a switch set at 7psi to determine if it has oil pressure, then moves the needle based on temperature, load, and RPM... the OE reading is a complete fabrication.

I have a REAL gauge on my dash, and the readings aren't even close!! The OE gauge never reads more than about 45psi, while the real gauge fluctuates from 25psi at hot idle to 60psi hot cruise (between shifts), to 80psi cold!!!

 

[BIGNASTY]

pre luber

Dont know if anyone likes these things as for me I havent had a car, truck without one. I had one on my class 8 trucks and got 1 million + miles out of a 3406 cat the same on a large cam cummins. The motors had the rods and mains rolled in at 100,000 without fail but the rest of the motor was untouched. I have one on the wifes M B and I have one on my Dodge. It takes less time than the preheater on the Dodge to have oil pressure no dry starts and NO NEED FOR LUCAS. Pre-luber Engine Products plus has turbo cool down