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Discussion Starter #1
getting an engine flush done today at costco... really cheap... and they're gonna put in castrol syntec... but 5w50 is all they offer??

is that necessarily bad for my engine?... I have a 2.7L :(
just wondering if anyone can shed some light on this...

I can change the oil to a mobil 1 5w30 in the near future... just want to make sure I don't have to do it right away

thanks for any and all responses

Mark
 

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I just changed my oil with Syntec 10W30. Not sure if 5W50 is ok to use?
 

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WARNING! Don't Do It!

Your 2.7 runs the heads quite HOT. All of our motors run the heads hot, but the 2.7 gets the hottest due to the DOHC. There are a LOT of little moving parts that need to be cooled up there and lubricated well.

When you put a thicker oil in, you SLOW DOWN the flow of oil. Oil doesn't just lubricate parts, it does a significant part of the cooling duties as well.. Would you put a coolant in your radiator that was almost twice as viscous? Of course you wouldn't!

Thick oil also puts more drag on the eingine, thus making it run hotter and killing mileage.

Puting thick oil in is just asking for sludge. I've seen it happen personally and it aint pretty.

Use Mobil 1 Extended Performance of the weight that the manual calls for. Syntec is probably no better than Mobil and Mobil is easier to find.

You may want to flush the engine now. Use Seafoam Motor Treatment, it works and is not as dangerous as the kerosene based cleaners. It cleans slowly, you actually drive the car with it in there!
 

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hardwareguy said:
Your 2.7 runs the heads quite HOT. All of our motors run the heads hot, but the 2.7 gets the hottest due to the DOHC. There are a LOT of little moving parts that need to be cooled up there and lubricated well.

When you put a thicker oil in, you SLOW DOWN the flow of oil. Oil doesn't just lubricate parts, it does a significant part of the cooling duties as well.. Would you put a coolant in your radiator that was almost twice as viscous? Of course you wouldn't!
When it's cold, the 5w50 will be less viscous than the 10W30, has excellent oxidation stability, and low volatility.

I wish people would understand how oil works. It drives me nuts when they talk about something like a 5w50 being "thicker" than a 10w30 etc.
 

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Discussion Starter #6
okay.... I've heard and read several things on the internet.... and havn't really concluded anything... it almost seems as if everyone's comments are their own preference?... I"m no mechanic... but I've even heard some people saying the get better milage from the 5w50...

I was hoping someone could explain this to me... cause I always thought that the 5 or the 10 in the 5w30 stood for the "thickness" of the oil.... 5 therefore making for easier cold starts etc...

I don't understand what the 30 or 50 means in 5w50 vs. 5w30?

does it really mean the oil is thicker... or better at protecting... I've heard of people running 5w30 in the winter.. and 5w50 in the summer?.... I've also heard of people running 10w30 in the summer instead...

anyways... I just picked up the vehicle... and seems to run a little nicer due to the flush...
I still get some engine tapping when accelerating past 3000 rpm... and I"m not sure what that is..

I have a jug and a bit of mobil 1 5w30 at home I can swap into the engine this week... it's not like I'll be running it on the highway anytime soon (which reminds me... I heard that people who are hard on their cars could use the 5w50 instead of 5w30.... specifically people who race their cars... which I don't)

thanks again for any and all comments..... I'm very interested in what people have to say on this...

Mark
 

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In a nutshell:

The W signifies winter and is the oil’s low temperature characteristics, while the higher number gives the oil’s high temperature viscosity properties. A 10W-30 oil behaves as 10-weight oil at low temperatures but gives the protection of 30-weight oil at the high engine operating temperatures.

er, that's pretty simplified.

You might read through this:

http://www.wearcheck.com/literature/techdoc/WZA007.htm
 

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Discussion Starter #8
so does that mean a 50 for the summer is better at protecting... but not as good at removing heat as posted above?
 

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Viscosity isn't the only thing that determines protection, and as far as removing heat, it's not going to make any difference at all. A 5W50 WON'T however lose as much viscosity at 100 degrees C as a 10W30 would.

Edit: you might check out the "Bob is the Oil Guy" site/forum if you really want to learn about oil, there are several tribologists there, and they really know lubricants: http://theoildrop.server101.com/ubb/ultimatebb.php

http://www.bobistheoilguy.com/
 

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hardwareguy said:
Use Mobil 1 Extended Performance of the weight that the manual calls for. Syntec is probably no better than Mobil and Mobil is easier to find.
Actually, Syntec is a LOT easier to find here. Mobil is like specialty stuff you've gotta look around for.
 

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5w-50 is for air cooled motorcycles
5w-50 is thicker than 10w-30, here are the Mobil1 kinematic viscosity numbers.
@40 celcius (100F) & @100 celcius 212F
5w-50 104.9, 17.5
10w-30 62, 10
The specific heat capacity difference isn't worth considering.
Castrol isn't a synthetic oil per se, but a really worked over regular oil, so the viscosity specs should be close.

On a cold start you need oil in the head, that isn't happening with 5w-50.

5w-30 Castrol syntec for winter, 10w-40 for summer.
 

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BadBob said:
When it's cold, the 5w50 will be less viscous than the 10W30, has excellent oxidation stability, and low volatility.

I wish people would understand how oil works. It drives me nuts when they talk about something like a 5w50 being "thicker" than a 10w30 etc.
When the 5W-50 is up to operating temps its more viscous than 10W-30, and is no good for a 2.7. Its springtime, who cares about the cold, its not relavant this time of year, unless you're in Alaska.

Don't use it. I can't believe the only weight they offer in a synthetic is 5W-50? Does anyone even use it?
 

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Discussion Starter #14
well I've decided to leave it in until I get an afternoon in the near future to swap it out... engine seem to be running better than ever after the flush and oil... maybe even better one I get it some mobil 1

thanks guys
 

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MikeW said:
5w-50 is for air cooled motorcycles
5w-50 is thicker than 10w-30, here are the Mobil1 kinematic viscosity numbers.
@40 celcius (100F) & @100 celcius 212F
5w-50 104.9, 17.5
10w-30 62, 10
The specific heat capacity difference isn't worth considering.
Castrol isn't a synthetic oil per se, but a really worked over regular oil, so the viscosity specs should be close.

On a cold start you need oil in the head, that isn't happening with 5w-50.

5w-30 Castrol syntec for winter, 10w-40 for summer.
5-50 isn't something I'd use in an air cooled motorcycle. 20-50 maybe, or 20-60 (your average harley will shear a straight 50 down to 30 specs in about 2000 miles).
It's kind of hard to compare the 5w50 syntec to the Mobil 1 stuff, some of the Mobil 1s are on the very low end of the viscosity for the stated product. For instance, you can find other sythetic 10w40s with a higher viscosity than that particular 5w50. Hell, even Mobil 1s own 0w30 has a higher "cold" viscosity than their 10w30 does (at 10.3, their 0w40 is 14.3).

Would you run Redline 10W40? it's specs are
102 15.3

Valvoline synpower 5W40 is close too
91.53 14.13

Yeah, the 5w50 has a slightly higher viscosity at 40C, would it make that much of a difference at cold start? I seriously doubt it. FWIW, Mobil has been putting some hydrocracked stuff in Mobil 1 for a while now from what I understand.

The moral of the story is, don't get brainwashed by the reccomended oil viscosity. Most of the US specs are much lower than the same vehicles in other parts of the world. Why? EPA mandated milage...

Edit: I lied, the real moral is, it won't hurt anything to leave it in the car for 3000 miles. Why waste money?
 

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BadBob said:
When it's cold, the 5w50 will be less viscous than the 10W30, has excellent oxidation stability, and low volatility.

I wish people would understand how oil works. It drives me nuts when they talk about something like a 5w50 being "thicker" than a 10w30 etc.
50 weight is more viscous than 30 weight, trust me, I have messed with both. 50 weight oil flows SLOWER than 30 weight, heck it even comes out of the bottle a bit slower.

Go to the parts store, and pick up a bottle of 5W50 and shake it, now pick up the 10W30, the 10w30 sloshes around more when shaken.

The xW rating is only comparable to oils of the same basestock weight! a 5W50 is thicker, even in the cold than a 10w30.

I have used 5W50 as a lubricant for small electric motors and hinges. I use it because it stays in place better than 10w30! That says alot! 50 weight oils make a great emergency lube for small electric motors, it will keep a motor running over the weekend before the motor shop opens on monday, even with scored bearings, the oil stays in. 10w30 doesn't work like this, it just kinda gets thrown out....

Also, I wasn't talking about when it is cold, my main concern is when the engine is hot. Although the startup wear will accelerate as well due to the fact that 5W50 is so viscous that it taked forever to get up to the heads.

That's when you start the fun. The flow is slower, so there the oil gets exposed to high temps longer, not good. I have seen what happens when people put heavier oils in and it isn't pretty. It's called sludge, I don't think we need an explanation to what sludge is.

Now, if the oil passages are large enough and the motor is hot enough, 5W50 might be OK, but the 2.7 has SMALL oil passages and while it is hot for most vehicles, it is still fairly cool rinning compared to other engines, like say an air cooled VW or an air cooled V twin.
 

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Discussion Starter #19
thanks for the post..... well I hope that in these last few days on the flushed engine the syntec didn't form any sludge... but I will swap it out for the mobil 1
 

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hardwareguy said:
The xW rating is only comparable to oils of the same basestock weight! a 5W50 is thicker, even in the cold than a 10w30.
The rest of your post is dead on and I agree with all of it. Except for the quote above. At cold temp, the 5W-50 will be thinner than the 10W-30. The difference being 5W and 10W. 5W, even though its upper number is 50, will flow better in cold temps than 10W. This time of year, either 5W or 10W will be fine, just when it gets below 0F then you'll need the 5W.

But I'm right there with you on the 2.7 and 50 weight oil. You do not want this in your engine. Matter of fact, if there is still any warranty on the engine, they will void it for using it. Using anything other than what the manual recommends will kill that. And with the 2.7 and its sludge issues, 50 weight is very ill-advised. Considre this, the newer 2.7's in the Sebrings are now running 5W-20, yes 20. Even thinner than before. A lot of newer engines are using 5W-20. My parents' Honda CRV uses 5W-20 and I had to open the hood and see for myself because I didn't believe it. So using 50 weight is overkill.

Another reason not to use an oil with such a large spread between the numbers is because there's a lot more viscocity improvers used to create the multi-viscocity oils. The wider the spread the more VI's they use and the faster it breaks down.
 
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