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Discussion Starter #1
Noticed that in the am a cold motor is raising my oil pressure to 8 on the dial @ 2500 rpm.

Hows yours compare?

FRIZZLE
 

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Shizzle, mine never gets that high under those conditions.

It goes just over 6. You do live in the country though and perhaps it gets colder than mine with the lake winds?

As always

H
 

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Discussion Starter #6
Murray - Mobil 1 - 5 w 50.

Although it's expensive, i've got cars with over 500,000k and still tight as a drum. Takes a bit of the nervousness out of the aftermath of flogging the engine.

FRIZZLE
 

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Frosty. you are using the wrong weight.

That's not the Recommended mobil 1 weight.

You need to use MOBIL 1 10W-30 or MOBIL SYNTH S 10W-40 or MOBIL SUPER S 10W-40 or MOBIL SUPER GF-2 10W-30 or MOBIL 1 0W-40

I think that's why your engine acting weird. Better change the oil.

Cheers
 

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When the engine is cold, pressure is around 6 on idle and climbs to about 7 on gentle acceleration.
When hot, pressure reads at 4 on idle and can rise upto 6-7 on hard acceleration.
 

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At warm idle I'm just under 2. Under hard acceleration it goes up to about 6-7
 

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Dayum! My pressure is at 60...psi. I assume you guys use kg?
 

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markers are at 0, 2, 4 (straight up), 6 & 8
 

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Normal for me. Cold 6 anything above 3k will go into the 7-8 range. Warm 2 idle just short of 8 if going hard. 10w40.
 

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Discussion Starter #14
Why would'nt 5 - 50 have a better protection range than say 10 - 30?

Or even just 30 grade?

don't understand. Maintaing good pressure under adverse conditions should be the aim, I would think.

FRIZZLE
 

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Originally posted by frosty@Oct 21 2004, 04:20 AM
Why would'nt 5 - 50 have a better protection range than say 10 - 30?

Or even just 30 grade?

don't understand. Maintaing good pressure under adverse conditions should be the aim, I would think.

FRIZZLE

don't know frosty. Sorry can't help.

The list that i gave you is the list that are recommended by Mobil.

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Yun
 

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Here we go,

Ideally, oil should be thin enough to flow easily when the engine is cold and remain thick enough to protect the engine when it's hot. The lab analyses of each oil's viscosity characteristics - its ability to flow-indicate that motor oils have improved since 1987, when we last tested them. This time, far fewer test samples failed to meet the viscosity standards for their grade - and those were typically outside the limits by only a slight amount. No brand stood out as having a significant problem.

We tested oils of the two most commonly recommended viscosity grades - 10W-30 and 5W-30. Automakers specify grades according to the temperature range expected over the oil-change period. The lower the number, the thinner the oil and the more easily it flows.

In 5W-30 oil, for example, the two numbers mean it's a "multiviscosity" or "multigrade" oil that's effective over a range of temperatures. The first number, 5, is an index that refers to how the oil flows at low temperatures. The second number, 30, refers to how it flows at high temperatures. The W designation means the oil can be used in winter.

A popular belief is that 5W-30 oils, despite their designation, are too thin to protect vital engine parts when they get hot. However, one of our laboratory tests measured the viscosity of oils under high-temperature, high-stress conditions and found essentially no difference between 5W-30 oils and their 10W-30 brand mates. But at low temperatures, the 5W-30 oil flowed more easily.

Viscosity grade is important, so be careful. Recommendations vary with the make, engine, and model year of the car, so check your owner's manual and ask the mechanic for the proper grade of oil.





If you want to read the Consumer Reports Article on 'The surprising truth about motor oils' heres a link to a copy of it.

http://www.xs11.com/stories/croil96.htm

The test involved 75 New York taxis with newly rebuilt engines using different engine oils for a while then check for wear etc.

"We put identical rebuilt engines with precisely measured parts into the cabs at the beginning of the test, and we changed their oil every 6,000 miles. That's about twice as long as the automakers recommend for the severe service that taxicabs see, but we chose that interval to accelerate the test results and provide worst-case conditions. After 60,000 miles, we disassembled each engine and checked for wear and harmful deposits. "

They are basically saying that there is very little difference between the different oils the companies make, including dino vs synthetic, but they did mention that different weights are important.
 

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Discussion Starter #17
Thanks Murray - in my mind it'still somewhat unresolved - but very interesting and getting more so.

In essence, from what you posted, a low number indicates the characteristics of the oil at the low temperature, ie-a weight of 5 means the oil is not too thick and flows quickly and efficiently to the places where it's needed.

Conversely, the high (50) number indicates the characteristics of the oil under extremes of temperature (heat) so a high number is advantageous (one would think). Thinned oil wouldn't be doing too much of a job under heavy engine loads. (?)

I'll look up a bit of stuff tonight - wonder if NATHAN could enlighten us.

And there's the thing with synthetic v. mineral also.

Who's the expert?

ps - maybe ratings beyond certain figures are money wasted for engines under average conditions?

I think that I've posted this before - I have a number of business vehicles - 2 of which have had nothing more than regular servicing and been "knocked around" by sales reps, AND BOTH NOW OVER 500,000k,
and you wouldn't know. Tight as a drum both - always had Mobil 1
synthetic in the engines.

FRIZZLE
 

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Yeah the 50 rating means the oil is still think at higher engine temps, and that seems to be showing in your oil pressure readings.

The thicker oil maybe protecting engine parts better in theory but if you've got the wrong one it could be doing other damage. You might not be too far off but the oil pressure readings are high so you might want to check the manual or just call Peter(non APS) and ask.

Sports Car International Pty Ltd
67 New South Head Road
RUSHCUTTERS BAY NSW 2027
Ph: 02 9328 6588 Fax: 02 9362 3152

Regarding the synthetic vs mineral,
Dont know who the expert is but I will always go synthetic oil for a piston engine. :)
 

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Thanks for the link Frizzle - now I have to make an hour of my time free to read.

You should ring Nissan and ask them what viscosity oil they use. From memory, its a 7.5W-30. I'd try and stay close to what the factory recommends - afterall, they are the ones that have invested $$$$ in designing and protecting the engine.

Having said that, all name brand oils these days are very good and will do a good job protecting your ingen, regardless of viscocity.
 
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