5w-30 vs 5w-40
03-31-2011, 11:31 AM
#1
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Join Date: Apr 2009
Location: Hilo
Posts: 466
Car Info: 14 m235i
5w-30 vs 5w-40
What's up everyone, here goes another noob question.
Since Amsoil is pricey and not readily available in Hilo, I've been pondering what motor oil to use. According to Nasioc and other forums, Rotella would be good.
My only question is the 30 vs 40 since the 5W won't apply to us. We stay warm all year so will the 40 be better or worse? Thoughts? Inputs? Thanks!
Since Amsoil is pricey and not readily available in Hilo, I've been pondering what motor oil to use. According to Nasioc and other forums, Rotella would be good.
My only question is the 30 vs 40 since the 5W won't apply to us. We stay warm all year so will the 40 be better or worse? Thoughts? Inputs? Thanks!
03-31-2011, 01:22 PM
#6
03-31-2011, 01:24 PM
#7
I went with Valvoline on sale at Costco but may switch to Rotella because of price, either way, it's in spec and Subaru will honor the warranty- the minute differences of oil to me is like the minute difference of dd'ing with a big spoiler, the nuances are only seen at very high speeds...
/opinion
03-31-2011, 07:14 PM
#8
If you don't have an oil pressure gauge you should run the stock weight.
Normally you pick the weight of your oil on your rev range and oil pressure. 10 psi for 1k of rpm is a good rule of thumb. if you spin 8k and don't see a minimum of 80 psi you're in trouble. Youd then step up the weight. Too much pressure is bad too, so the weight helps to get the desired pressure.
Normally you pick the weight of your oil on your rev range and oil pressure. 10 psi for 1k of rpm is a good rule of thumb. if you spin 8k and don't see a minimum of 80 psi you're in trouble. Youd then step up the weight. Too much pressure is bad too, so the weight helps to get the desired pressure.
03-31-2011, 07:23 PM
#9
If you don't have an oil pressure gauge you should run the stock weight.
Normally you pick the weight of your oil on your rev range and oil pressure. 10 psi for 1k of rpm is a good rule of thumb. if you spin 8k and don't see a minimum of 80 psi you're in trouble. Youd then step up the weight. Too much pressure is bad too, so the weight helps to get the desired pressure.
Normally you pick the weight of your oil on your rev range and oil pressure. 10 psi for 1k of rpm is a good rule of thumb. if you spin 8k and don't see a minimum of 80 psi you're in trouble. Youd then step up the weight. Too much pressure is bad too, so the weight helps to get the desired pressure.
04-01-2011, 04:48 PM
#14
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Join Date: Dec 2009
Location: Ice Palace...not the meth lab, the skating rink.
Posts: 965
Car Info: 1995 dodge neon
I run a mixture of O'riley, penzoil, valvoline, quaker state, gas station brand, differential fluid, automatic transmission fluid, fox shock oil, or whatever the frig is laying around...
It's just oil, unless you are racing and kitting 8k all day, I doubt you or your car will ever notice a difference other than price. I hope that all of that advertising hasn't done too much damage.
You can run synthetic and change it every 1500 miles...and still have an engine crap out on you.
Have you ever noticed that when you change your oil, you dont have oil pressure for a couple of seconds after the car is started. I'm not a rocket surgeon or anything, but I would say this is a bad thing.
The number one enemy of your engine is driving it before it reaches operating temperature. This is where most of your wear happens, and the most fuel/carbon mixture (the stuff that makes your oil black) is introduced.
Air/oil separators are an enemy of a long lasting engines also. Some of the combusted air/fuel squeezes past the piston rings, it creates a positive pressure in the crank case.
These gases blow by the piston rings mix with the oil and pick up some creating a air/oil mix.
The factory PCV system does a great job of solving this problem. It is hooked up to the turbo inlet hose so the vacuum created in the turbo inlet when the car is running pulls this air/oil vapor into the engine so it gets burnt.
This vapor lubricates the cylinder walls and valve stems...allowing your engine to run longer with less wear.
The downside of the oil vapor in the intake is a slight octane reduction. Not good for dyno numbers. (this is why it makes sense in a race car, or a toy that you don't rely on to get to work)
The point of my rant:
Use whatever oil is on sale (you can send me a check for the money I saved you, instead of giving it to the guys that advertise best)
change conventional oil every 5-6k
change synthetic oil every 10-12k
Allow your car to warm up before you rev past 2500
Don't use a catch can or AOS if you care about engine longevity
Don't listen to hype. Even the dealer will tell you to change your oil every 3k, they want your money (and will almost always try to upsell you on something).
Check out a BMW service manual. It will tell you to change the oil every 15000 with synthetic.
It's just oil, unless you are racing and kitting 8k all day, I doubt you or your car will ever notice a difference other than price. I hope that all of that advertising hasn't done too much damage.
You can run synthetic and change it every 1500 miles...and still have an engine crap out on you.
Have you ever noticed that when you change your oil, you dont have oil pressure for a couple of seconds after the car is started. I'm not a rocket surgeon or anything, but I would say this is a bad thing.
The number one enemy of your engine is driving it before it reaches operating temperature. This is where most of your wear happens, and the most fuel/carbon mixture (the stuff that makes your oil black) is introduced.
Air/oil separators are an enemy of a long lasting engines also. Some of the combusted air/fuel squeezes past the piston rings, it creates a positive pressure in the crank case.
These gases blow by the piston rings mix with the oil and pick up some creating a air/oil mix.
The factory PCV system does a great job of solving this problem. It is hooked up to the turbo inlet hose so the vacuum created in the turbo inlet when the car is running pulls this air/oil vapor into the engine so it gets burnt.
This vapor lubricates the cylinder walls and valve stems...allowing your engine to run longer with less wear.
The downside of the oil vapor in the intake is a slight octane reduction. Not good for dyno numbers. (this is why it makes sense in a race car, or a toy that you don't rely on to get to work)
The point of my rant:
Use whatever oil is on sale (you can send me a check for the money I saved you, instead of giving it to the guys that advertise best)
change conventional oil every 5-6k
change synthetic oil every 10-12k
Allow your car to warm up before you rev past 2500
Don't use a catch can or AOS if you care about engine longevity
Don't listen to hype. Even the dealer will tell you to change your oil every 3k, they want your money (and will almost always try to upsell you on something).
Check out a BMW service manual. It will tell you to change the oil every 15000 with synthetic.
Last edited by spinplay01; 04-01-2011 at 04:51 PM.