Well changed my oil this past weekend just after breakin, 1400 miles. Put new Penzoil 10w30 and a new Nissan filter, took about 5 qts to get it to the top dot on the dipstick. Anyway, now when I rev the car over 3K the oil presssure guage shoots up to 120 with every rev. Sits around 60 at idle. Is this normal? I don't remember how the guage behaved before the change so I don't know if I'm being paranoid or not. Could the slightly thicker oil I chose be boosting the oil pressure? am I hurting my baby?!
Thanks,

Sarg

 

You are being paranoid.

 

OK, just weird cuz I don't remeber the OP needle moving around that much. It pegs 120 by 4K. weird.

 

My 07' is the same way. My 06' was never that high i'm not really sure why. It might be because the oil pump is a much stronger unit on the 07's but I try not to look at the gauge because if it was actually dangerous something would have happened by now.

 

I notice my oil psi running a little higher after a fresh oil change. 10w30 Castrol dino oil with K&N oil filter... Your 60psi at idle & 120psi at 4k rpm seems high to me for an engine that is fully warmed up. Mine is 30psi at idle & 90psi at 4k rpm.... Just hit 3,600 miles on the odometer...

 

I'm pretty sure mine is inaccurate.

 

why so thick an oil? PP 10W-30 is good stuff, but their 5W-30 would be better for start-up conditions.
Will

 

I thought that, but our summers get pretty hot here so I figured a little thicker would be easier on the engine, not the best for fuel economy according to the manual though. I'm keeping an eye out and will update, apparently its not just me. phew...

 

It's cool, just an fyi though, keep in mind that when the engine is up to temperature, both oils will be about the same viscosity. The first number refers to how thick the oil is when it's not up to temp (as measured at 40 deg C). The thicker the first number, the thicker it is at start-up and that's not usually a good thing. Being hot where you live, it's not a serius issue or anything, but you're not doing your engine any favors with it over the 5W-30 or an 0W-30.
Will

 

hmmm thats weird, I thought it was the 'range' of thickness an oil has. In other words it will get no thinner than 10 but no thicker than 30. Thanks for the edumucation!

Sarg

 

You're right in thinking that the oil weight, when a multi-grade oil, is a range of the oil's thickness when cold and when hot. The "W" is the "winter weight" of an oil and is the measured viscosity of the oil, in centistrokes, at a temperature of 40 deg C. The second number is the measure of the oil's viscosity at 100 deg C in centistrokes. So, your 10W-30 is a measured 10 weight oil when cold, and a measured 30 weight when hot. But, remember that an oil's viscosity gets thinner with temperature. So, if a 30 weight is technically thicker than a 10 weight at the same temperature, then as the oil heats up, and the oil thins out, a 30 weight is still going to be thicker than a 10 weight at that same heated temperature even though it has thinned out with heat. An example of this with your 10W-30 and a 0W-30:

Pennzoil Platinum 10W-30 pumping viscosity numbers at each measured temperature:
@40C= 72.7 cSt, @100C= 10.5 cSt

Amsoil 0W-30 pumping viscosity at each measured temperature:
@40C= 56.9 cSt, @100C= 11.2 cSt

The PP 10W-30 is much thicker than the 0W-30 when cold. The higher number, in cSt, means the oil doesn't flow as well and the engine must work harder to pump the PP when it is cold compared to the Amsoil. When the PP oil heats up, the oil thins out. But, it doesn't stay a 10 weight oil when hot- and for good reason! A 10W would be too thin when hot to protect the engine, with a cSt @100 deg C of only 4.1. Because the oil is a "multi-grade" oil, it contains a chemical additive package known as a viscosity index modifier or viscosity index improver. These additive packages react with heat to "thicken" up the oil so it behaves like a 30wt when hot. The PP has a cSt of 10.5 and the Amsoil a cSt of 11.2. Each is obviously thicker than a 10 weight oil at 100 deg would be. This multi-grade oil allows the engine a decent amount of protection that a straight 10 weight wouldn't be able to give, but with better cold start oil flow a straight 30 weight couldn't provide. In this respect, the Amsoil is a great oil because it flows better than the PP when cold but becomes thicker than the PP when hot for good protection. This is the beauty of multi-grade oils.
Will

 

why not just use 5w30 like the manual says?

 

i run Royal Purple 10w-30 in my 06

 

Good call on the Amsoil. I went out and got some Amsoil 0w30 this afternoon... Looks like pretty good stuff. :-)

 

cuz I had a case of 10w30 sittin around.

 

I live in Hot South FL, I have an extra case of Amzoil 20w 50 racing oil that I would love to use. Currently I'm using Royal Purple 5-30 as nissan calls for. Anyone have any thoughts?

 

I would stick with what manual recommands which is 5W-30

 

Some nice oil information in the top 100 questions thread, and in your OWNER'S MANUAL