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What oil ??

C

cmegga

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Just wondering what everyone runns for a summer oil.

I just had here rebiuld and bored 20 over. Im looking for a good oil to protect and keep her cool. My mechanic filled it up with 10-30 after the rebuld and I did the same with the next oil change.

I just cant help but think this is way to light to really protect well. It looks like water on the dip-stick.

It around a 350 hp engine and it was alot or cash to build so I want something that will be the safest in there. Plus she runns a bit hot now thats is 20 over.

Can I get away with a 20-50 in the summer or is that too heavy ??
 

Evolution1980

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If you've already done the break-in on the engine, and your outside temp is usually hot (above 75° most driving days), you can probably go with 20-50.

I run Mobil1 Fully Synthetic 15-50 in the summer, then change it out to 10-30 in the winter for storage.
 

Tom73

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I run Mobil 1 year round here in central Texas. Usualy 5w30 or 10w30.

tom...
 

Evolution1980

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Tom73 said:
I run Mobil 1 year round here in central Texas. Usualy 5w30 or 10w30.

5-30?!?! in TX? I'd definitely recommend AGAINST that... waaaay to thin, especially if it's synthetic. 10-30 is the recommended for daily driving in most V8's. If it's any type of performance engine, or driven as such under hot conditions, you'd want to go the other way towards the 15 weight, not 5!
 

cntrhub

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Believe it or not, using 5-30 is fine for year round use. Here's why. Dyno tests (on high hp output motorcycle racing engines) have shown that running thinner oil, increases horsepower. Not only can you run this without problems, you'll be ready for winter months as well.
Another good reason for using thinner oil, is to move the liquid faster, to reach those moving parts. Using thicker oil tends to slow the process down. Think of it as turning upside down a bottle of catsup and a bottle of water... which moves faster?
Oil retains heat! Having more oil (over filled) in the crankcase, will increase the temperature. Hope this helps to explain a few fallacies about the mystery of oil.
 

Evolution1980

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I read differently in an industry mag (either on some oil mfg website, or in a reputable magazine) at one time. But I'm at work and don't have the time to hunt down the info :( I'd say it's probably a matter perspective, just like cross-drilled -vs- solid rotors.

I'd also question somewhat the fact that this came from a motorcycle engine review. Combustion engines, yes. But overall a relatively different breed of engine. (Not a point though that I'm well versed in enough to put up friendly argument :)
 

Tom73

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5w30 is the recommended fill for new vettes. But the reason that I run it is that most wear occures on engine start up. I want to oil to get to those parts as quickly as possable. There is almost no wear on an engine that is crusing down the interstate. Probably about 90% of your engine wear is on start-up, so I keep it thin to get the oil to the parts that really need it.

tom...
 

Evolution1980

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If that's the case...you're already too late :D You would want to look into a pre-oiler if you're concerned about that. Thicker oil would adhear to the parts better, as opposed to thinner oil running off them faster after the car's been shut down.

As for oil retaining heat, yes, it does to an extent. It's supposed to. That's so it pulls the heat from the moving parts into the oil, then as it's circulated it gets disappated.

It's all in persepctive :D hahahahah....


So there ya go, CMEGGA, two differing opinions. I'd take this over to another message forum within CAC. Hell, this is the kinda thread can get everyone involved with their own 2 cents. I'm sticking with my 10-30 :D

Tom73:
You may be on to something, as far as newer engines are concerned :D
http://www.c5-corvette.com/factory_oil_fill.htm
 
C

cmegga

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Wow looks like a hot topic.

But Im still wondering if something heaver ( above the 10-40 I have in it now) would be better protection, and how heavy can I go safely ??
 

77-4speed

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If you read the link in the last post by evolution, the Mobil engineers say that you should go with the lightest lubricant that is rated for your temps. Its as simple as finding the hotest temp you think you'll see during the oil usage and choosing the corresponding lightest oil. The heavier oil will not benefit you and in fact will only reduce horsepower.

Russ
 
P

page62

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I'm gonna be contrary here...use a straight 30 HD oil in your engine during the summer months!

The problem with multigrade oils is they start with the lighter weight (e.g., 5w or 10w) then add viscosity improvers to acheive the heavier weight. As the VI's break down under extreme conditions, guess what?

Single-grade oils start with the actual weight oil (e.g., 30 or 40 weight). Many mechanics in this part of the country recommend this oil for year-round use!
 

Jack

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First, I don't KNOW this ... but I suspect the newer motors (using 5-30) are manufactured-assembled with closer tolerances (and less overall clearance) than in days of old. Maybe they use newer alloys to make todays parts; pieces that are routinely fitted much tighter than in the past. Maybe the plants' newer machining centers are CNC-based and will maintain closer tolerances. So, IF the newer motors are built with closer tolerances (and less overall clearance) then they should benefit from lighter oils. On the other hand, motors with more clearance may need a bit heavier oil (or an increased volume ... or both) to compensate. Regardless ... In summer, I would not hesitate to use 10-40 (either dino or syn) in an older design street motor that's in good condition. Maybe I'm wrong but for a street car I've always held that as long as there's plenty of clean oil it makes little difference what brand or whether 5-30/10-40/20-50. I'd like to hear from Ken on choosing weight ... Ken's worked with & studied oils... maybe he can step in too.
JACK:gap
 

Evolution1980

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77-4speed said:
the Mobil engineers say that you should go with the lightest lubricant that is rated for your temps. Its as simple as finding the hotest temp you think you'll see during the oil usage and choosing the corresponding lightest oil

OK...so what temp is it that you are referring to when you say rated for your temps. Oil temp? Outside temp? Operating temo? Max operating temp?

And then where do I find the description of the different oils usage temperature? I don't recall on the back of my qt of Mobil1 it saying "OK...if your temp is between ### and ###, use this oil. Otherwise, choose our other oil #w-##" Usually they say "higher operating temps, performance engines,..." etc... And, the higher the performance, the higher the oil rating in viscosity..

(Now I'm posting just for the sake of conversation :)
 

77-4speed

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Yes, when the oils break down they do tend to go to their original weight. If you have true synthetic oil in the car long enough for it to break down, even if you autocross in death valley, you have no business driving a corvette or any car for that matter :) Synthetic oils can last for 25,000 miles easy. If you talk to a synthetic oil engineer as I have (I'm an ExxonMobil engineer) they will tell you that the only reason to change a true synthetic before 25,000 miles is because people are overly cautious and you never know when some sort of debris might somehow get into your oil stream and start wreaking havoc. Even under extreme duty driving conditions, synthetic oil will not break-down in the recommended 3000-5000 mile oil change interval. Unless of course you are using it in a NASA application, oh wait, they do use it in NASA applications, never mind :) :)

Russ
 

JHL

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I currently use Valvoline 15-15 and it seems ok and is only $9 a gallon, I was using Valvoline Racing for a time but it became difficult to get, expensive and for what benifit ??? but I did get a nice sticker from the guy on the counter.

I am going to go against all that is said and I do have a set of flame proof coveralls in the garage, I don`t think it matters as much as people in make it out. First of all it is the one job I have always hated doing and second it is becoming more and more difficult to get rid of the old oil if you do it yourself. Sure the oil companies and lube shops like it when you change every 3000 miles but imho you are wasting your money.

I used to recycle it by starting off with decent oil in my best car and then drain it and put in the next best one and so on. I have the Vette and 3 daily drivers so you get the picture. My VW has 131,000 and in my 10 month ownership I have put 14,000 on it and one oil change, I have a small GM compact has 160,000 with about 30,000 in my hands and one oil change, both were done with the cheapest oil in the shop and both still run like tops with good oil pressure. If you have a look in the handbook of some new cars they recommend upto 25,000 between changes. I have actually owned some cars that I never changed the oil in at all and I have only ever blown one motor in 24 years of driving.

J.
 

Tom73

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Jack said:
On the other hand, motors with more clearance may need a bit heavier oil (or an increased volume ... or both) to compensate.
Correct, if you have a worn engine you need something, anything, to fill the bearing gaps. But on an engine that is within specs you do not need a heavy oil. A heavy oil is harder to pump, is harder on lifters, puts more pressure on the distributor shaft/gear, takes longer to get to the top and then takes longer to run back to the pan. Nothing good there.

tom...
 
W

wolf_walker

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JHL, no offence, but that's nuts. In the US atleast, oil is cheap, and you can have it recycled for free. I've had way too many motors apart and seen all the black crud in them from old oil.
ANY internal combustian engine will deposit combustion byproducts into the oil over time, the oil itself may last a long while, but being constantly contaminated is hard on it. Anything that goes from a nice amber color to pitch black is not going to last that long without loosing something, that's about as simple an observation as one can make. Have an oil anylasys run sometime and see what turns up. It's only just recently that late models have started haveing extended oil change intervals, mostly because of either synthetic oil or much improved combustion effecniency. But there your cars, so..


On the oil weight issue.

The two reasons for light weight oil being spec'd for newer cars are 1: they are, as was stated, made to tighter tollerences and run much more effeciently overall than older motors. 2: Especially on small displacement motors, a heavy oil can have a noticable impact on emmesions and millege through parasitic drag, even a V8 will rev more freely with 5w30 than 20w50. That being said, perhaps a fresh and well built older motor would be fine with a light oil, but not most of them, in my experience. You take your normal everyday 100K mile chevy 350, it will rattle and knock slightly and generally just sound bad with a light oil in it, but fill it with 20/50, and a lot of that goes away, along with gaining higher oil preasure. Personally I like a pretty thick oil, I've never had a motor in good repair take more than a second and a half, even in pretty cold weather, to build oil preasure with 20/50. That's with a mechanical gauge. The drag is neglagable when weighed agenst the possible breakdown of lighter oil when under high heat and stress applications. There is also the issue of the viscosity modifiers used in lighter oils like 5 and 0 w 30, there not a really great thing either. This is why most true "race" oils are strait 30 weight or so, they also dont have to deal with many cold starts, which is the only reason for the multi viscosity that I know of.


Evolution1980, the outside air temp is the one refered too. You can find that in the manual for the indevidual vehicle. Now if it's an old vehicle, oil has improved some, so who's to say if it's accurate. For example, I have these handy...

For my 78 Lincoln, 460 4v..

5w30 is good from -20 to 100+ F
10w30 is good down to -18 and up to 100+ F
30w is good down to 4 and up to 100+ F
No mention of 20\50
This thing has 214K miles, it has run 10/30 for the first 100K, and 20/50 since then. Holds 60psi hot at 2Krpm, that drops some and it makes various noises with lighter oil, but it's solid as a rock with 20/50.


For my 81 VW Diesel..

5w30 is not recomended at all
10w30= 0 to 60 F
20w50= 15 to 78 F
Only thing rated for over 80 is 40wt
So technicaly my 15/50 is to light for most places I drive in the summer. My experience has not proven that, 20/50 was fine for a long time in several motors, I'm now running Mobil 1 15/50 as sort of an experiment. And still changeing at 3-4K miles, if you've ever touched used diesel oil you'll understand.


Those are the only specs I have handy, and if they were to write them today they would likely be different, as oil has improved quite a bit. The trick is to not mistake oil claims because of actual oil imporvement, and those made becasue of modern effecient motors. The VW's a good example, the new TDI's can run 10K miles on an oil change with specific synthetic diesel oil, this is proven by oil anylisys, but would I run my trusty old two decade old 1.6 that long? No way.
 

Tom73

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Wolf Walker,
I just pulled out the owners manual for my '90 Vette. It says to use SAE 5W-30. It does go on to say "Although SAE 5W-30 is best for your car, you can used SAE 10W-30 if it's going to be 0 degrees F or above." No mention of any other oil weight. And this was before synthetic oil.

By the way, as for the amber oil turning black...if yours does not darken you have some serious problems. One of the functions of oil is to carry the "dirt" back to the filter. If it is not turning black it is not doing its job.

tom...
 
W

wolf_walker

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1990 is not pre-synthetic, my 81 VW glove box manual evan mentions them. Germans always seem to be ahead though.

Oil color is directly relarted to how much combustin by-products are suspended in it, that is indeed part of it's job. If it was a perfect world it would enter the filter black and come out amber again, but it does not. It's engenered to hold the harmfull to metal chemicals that are left over from the combustion cycle suspended, and the additive packages nutralize it as best they can, those additives loose there effectiveness over time and with use, just like coolent. In a diesel, which is much more dependant on good oil overall, it must suspend the soot generated by burning diesel, hence the special diesel rateings. In most diesel's, and certainly any VW diesel, (inline 4 OHC), when you pour oil in the top of the motor, by the time it reaches the oil pan, it's black as the proverbial tar, which is as it should be. On that Lincoln I mentioned, it's like clockwork, when you hit 3000 miles it starts, in the next 600 miles, to turn from amber to black. Prior to that 3K mark, it's pretty much out of the bottle oil colored. That is a very clean and well kept motor with very little blow-by. That's been my experience with every motor in good repair that has been well cared for. If the oil is turning black before 3K miles or so, nine times out of ten it has an objectionable amount of blow-by from worn or ill-seated rings and/or valves/seals.

A 90 motor is probibly new enough that the lighter oil would be fine, and also quite possibly the parasitic losses from running 20/50 would be enough to make it not pass emmesions and millege specs for that year, hench GM would not recomentd a heavier oil for it, that would risk the wrath of the EPA. If you'll notice, 20/50 does not carry the EPA "energy conserving" star symbol, for just this reason.

Interistingly, my newer shop manuals for the Lincoln list 5w30 as the prefered oil also, I don't have the original manual handy to see what it called for, but I think it was 10/30 or 30wt. The same VW manual that mentions synthetics in 81 dosent even list 5w30, and 10w30 is only listed for up to about 50 farenheit. I imagine those motors were a bit harder on oil than a chevy v8.

Interisting stuff, however I'll keep 20/50 in older motors that just plain old sound bad with anything less, and keep changeing at 3K miles. That's consistantly gottem me over 200K on domestic motors and as much as 400K on VW's.
 

cntrhub

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I'm an old motorcycle racer back in the early 1970's. I was an, "A" sponsored rider. Meaning, I would receive "unlimited" cases of oil. I used to use straight 50 racing oil in the van. The down side of this, was hearing a ticking lifter, literally for over 2 minutes. Eventually it went away when warmed up. I never had an engine problem traveling throughout the country. So here is a little proof of using straight oil causing little or no damage.
I did call Mobil (not my old oil sponsor) just a few months ago, and asked about the shelf life of oil? If true, he stated that oil will last 500 years! I still have enough cases left over to last the rest of my driving career.
And yes, I do mix and match oils with all my vehicles. None burn oil. And I never experienced an engine failure caused by different weights/brands of oil used in the same crankcase.
As far as oil turning black, this is caused (mostly) by poor ring seal. I have 90K on my 4.3 S-10. I changed the oil about 2k mile ago and checked the color for this posting. It is dark amber in color, but not black. I guess my multi grade/straight grade oil change is doing fine.
 

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