Chuck S

Thicker oil will increase the oil pressure 'cuz it's resisting flow. Flow is vital. Blackstone Labs (an oil analysis shop some of us use) published their results of using 0W-20 oil in several engines and not seeing any wear not present with 10W-30. Spec for our cars remains 10W-30.

-- Chuck

Fraley

Current Oil Pressure

Cold Idle: 85-90 psi
Idle at Temp: 12-20 psi
Over 3K: 72-84 psi
VTEC: 77 psi

I saw it drop to 8 psi at hot idle after driving my car around for a long period of time.

rrounds

Didn't you get your answer in your other thread? 8 to 12 at idle is low. You have two options, rebuild or thicker oil. I would go with a 15/40 and see what your pressure is with that oil. Or you could start a third thread.

ROD
p.s. I would take off the oil filter(no need to change the oil) and cut it open to see if it has any metal in it.

Fraley

Well the whole point of this thread was asking if anyone had experience with Amsoil 10W-40 Premium protection and if switching from castrol to the latter would actually raise oil pressure or just cause a false sense of higher oil pressure. This thread was never meant to be another "Hey I have low oil pressure help" thread. It just kinda ended up going in the same direction. If any of the admins wants to delete either or, that's fine. I think I found my answer from Windhund116 and his link to bobistheoilguy.com. Apparently 10W-30 and 10W-40 have the same cold start viscosity and a different viscosity at temp which is what I was looking for.

p.s. I just don't feel comfortable putting diesel oil in my car, something just doesn't seem right. If it works for you than kudos but I don't want to loose any sleep over it. Thanks though!

rrounds

If you think a 10/40 and 10/30 are the same at cold temps take a look at Mobil Super, same goes for Mobil 1 H/M
Look at the cSt@40c 68.8 for the 10/30, 105.8 for the 10/40

This is 10/30
API Service Classification SN
Gravity, API 31.3
Specific Gravity 0.8693
Pour Point, °C (°F) -36(-33)
Flash Point, °C (°F), ASTM D 92 230(446)
Viscosity
cSt at 40°C 68.8
cSt at 100°C 10.5
CCS, cP 6,300 @ -25ºC
MRV, cP 17,000 @ -30ºC
Viscosity Index 140

and here is 10/40
API Service Classification SN
Gravity, API 31.5
Specific Gravity 0.8681
Pour Point, °C (°F) -33(-27)
Flash Point, °C (°F), ASTM D 92 240(464)
Viscosity
cSt at 40°C 105.8
cSt at 100°C 15.2
CCS, cP 6740 @ -25ºC
MRV, cP 27,500 @ -30ºC
Viscosity Index 152

Also look at the Mini-Rotary Viscometer and Cold-Cranking Simulator both are higher in the 10/40 than the 10/30 and this is at -25 and -30c

ROD

Fraley

Ok, then what is the major difference in the 2? Does switching to 10W-40 adversely affect the engine in cold starts? I read that Castrol is thinner than a standard 10W-30 which is what I use currently. If I switch to say Valvoline 10W-30 could it have the same effect as switching to 10W-40?

jyeung528

depends how cold it is at the cold start.

just try the oil and see what happens, good luck.

jyeung528

oh, back to my question, why not try to 5w40 amsoil?

rrounds

Because he has LOW oil pressure at idle and a 5/40 wil not help his idle pressure. He needs a little thicker oil when cold(and you can't call Florida cold).

ROD

rrounds

No it(10/40) won't hurt your engine. Like I said I've been using M1 10/40 HM for 80k miles. You need to find the cSt, CCS and MRV numbers for any oil you use. That is the only way to know how thick/thin it is when cold and hot.
By the way some 15/40 oils have a cSt@40c 109 and the Mobil Super 5000 10/40 I would use to see if that helped my oil pressure has 105.8@40c So you see you have to look at the numbers to know if its thick or not.
I would still open up the oil filter to see if its clean or not
Here are some picks of oil filters that came off of S's in my town
Oil Filters by Rod Rounds | Photobucket
Spread the pleats and see if you have much if any metal.

ROD