oil viscosity for over-redline rpm?

Messages
26
Location
Toronto ON
Hey everyone. Looking for some advice. I own a 1998 Grand Prix GTP, 3.8 S/C engine (iron block). We redline at 6000, determined by our oil pressure I assume, and I want to spin my engine a little past that to say 6300-6500. Our engine is rated for 10W30 oil. People spinning to these rpms currently have said they simply use a good 10w30 synthetic and change it often. I was wondering if I would be wise to use a slightly thicker oil so that it clings a little better to the crank and cylinder walls? Does anyone have experience with this scenerio? Also at the moment I keep switching between Castrol Syntec and Mobil 1, I can't decide which I like better. Mobil 1 seems to be a favorite on this board. I've also been thinking of trying Redline, I don't mind paying for a good oil. Any recommended brands are also appreciated. thanks!!
 

J

Messages
434
Location
Berkeley
quote:
Originally posted by Will: Hey everyone. Looking for some advice. I own a 1998 Grand Prix GTP, 3.8 S/C engine (iron block). We redline at 6000, determined by our oil pressure I assume, and I want to spin my engine a little past that to say 6300-6500. Our engine is rated for 10W30 oil. thanks!!
[Eek!] Super charged and you want to go past the red-line?!? [crushedcar] Well, I don't know of any oil named maniac-wants-to-go-past-redline, but as you say there is an oil named redline. So, use it. It's expensive, but nothing's too expensive for you wild-thang ! [Cool] I was going to recommend Mobil 1 15W-50, but I take that back. Use a good old group V oil with tons of Moly because nothing liquid is going to stick around in your rod bearings! [crushedcar] Oh by the way, please give me your VIN number. I want to stay far away from your car when it comes onto the used car market. [Freak] [freaknout] [Cheers!] Jae
 
Messages
313
Location
Jefferson, Wisconsin
Calm down there man.... going past the redline by 300rpm isnt the end of the world. Will, have you done anything to the GTP where you would move the powerband up and need to rev higher? 6500rpm would be silly unless you have done a cam swap. Remember, the high RPMs are a lot harder on the trans too. I would say stick with Mobil 1 SuperSyn 10w30 and just change it more often if you want. Redline is double the price of M1. Just change M1 2x as often [Wink] In my 11 second Z28, I tried using Redline, but after a day or two of drag racing (30 or so passes), I usually change the oil. With the Redline in, I didnt really want to since it is the equivalent of liquid gold, but it felt odd leaving the oil in. I would much rather use M1 becuase it costs less allowing me to change it more often. [ April 05, 2003, 02:34 AM: Message edited by: Intelman34 ]
 

J

Messages
434
Location
Berkeley
quote:
Originally posted by Intelman34: Calm down there man.... going past the redline by 300rpm isnt the end of the world. I would say stick with Mobil 1 SuperSyn 10w30 and just change it more often if you want. Redline is double the price of M1. Just change M1 2x as often [Wink]
Hi, I was half kidding and half concerned about a super-charged engine which is run past the red-line. [Big Grin] Don't you think Mobil 1 15W-50 has a better chance at staying in the rod bearings? It has a good additive package which includes moly. It doesn't cost any more than 10W-30. Will, I was just kidding and razzing you [Razz] [Cheers!] Either Mobil 1 15W-50 or Mobil 1 10W-30 will work well for you. [Cheers!] Jae [ April 05, 2003, 02:42 AM: Message edited by: J ]
 
Messages
43,676
Location
'Stralia
I'd guess that at extreme RPM, there's such an oil mist in the crankcase that the viscosity isn't an issue. Long as there's enough oil getting picked up to pump to the bearings, then no reason to change anything. (A guy I used to know had this super burnout Gemini, which had insufficient drainback at extreme revs. Oil pressure plummeted, engine died)
 

Patman

Staff member
Messages
22,017
Location
Guelph, Ontario
Normally I would say to go with Redline here, but have you priced it in Toronto lately? Lowest price is $15 per quart. So it's double that of Mobil 1. My recommendation: Castrol Syntec 0w30 But use the new stuff with the red 0w30 label which says made in Germany. This stuff is thicker at 40c than 10w30 and thicker at 100c too (it's very close to being a 40wt oil) It has a higher HTHS than Mobil 1, and is $6.66 per liter, vs $7.12 for M1. So far only Walmart has this new oil. Be sure not to buy the old 0w30 which has the yellow 0w30 label, that's old junk.
 
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5,785
Location
Dixie
Will, I'd also consider the Amsoil 10w-30 (product code: ATM) ....It works very well in these 3.8L GM V-6 engines. If you go to the Amsoil website you'll see it's been reformulated and now meets the most stringent ACEA "A3/B3/B4" specifications, one of the only 10w-30's to do so. If it was 5% thicker, it would grade out as a 10w-40 .... TooSlick
 
Messages
34,480
Location
NJ
quote:
This stuff is thicker at 40c than 10w30 and thicker at 100c too (it's very close to being a 40wt oil) It has a higher HTHS than Mobil 1,
M1. It's cheaper, you can find it anywhere and will perform as well as any of them. Specs. don't mean much bc most high end oils are very close. I'd also go with M1 because it's lighter and will flow better then the Amsoil and Redline. Bob has noted that Flow seems to be one of the most important qualities to look for. So the light wt. won't hurt anything and might even improve wear numbers over the othes. Patman, I'm not so sure thicker is better. Even though HT/HS will be higher with a thicker oil, I havn't seen any analysis to prove it. I think the reason Vettes use 5w-30 M1 is for better Flow. More oil where you need it when you need it. I've been reading all the analysis data and I just don't see where M1's light 30wt. becomes a problem. I used to think this was the oils biggest down fall, but after Bob talked about Flow, it makes sense. Even the oil study proves how well it's holding up. Can't ask for much more then that. [Smile] [ April 05, 2003, 08:24 AM: Message edited by: buster ]
 
Messages
401
Location
Southcentral PA
I don't think the redline specification has anything to do with limitations of friction or lubricating capabilities. While oil film thickness varies reasonably linear with engine speed, kinematic motion and the related stresses increase exponentially with engine speed. Engine speed is mostly limited by the ability of components to handle rapid cyclic motion, which has a lot to do with the weight and strength of these reciprocating components. You may be able to run an engine well past redline and get away with it for as long as you own the car. But if you took 10 cars and did the same thing to them, some would certainly see damage. You see, the redline is set so that the stress and working limits of the components does not exceed the worst-case fabrication defects, assuming red-line is only a certain % of the overall usage of the car. Hit redline frequently and beyond, you will be "using up" the designed life and factor of safety of components. Certainly using the best possible oil (with excellent film strength) will help to avoid certain problems unrelated to component strength and balance. But it's only a small part of the picture. If you want to run a car above the manufacturer's redline, you will need to make sure you have components that have materials, manufacturing procedures, and weight balance that exceeds the manufacturer's specifications. This would probably include valvetrain components and connecting-rod/pistons. [ April 05, 2003, 09:14 AM: Message edited by: S2000driver ]
 
Messages
188
Location
Evansville, In.
I think he ought to run a light 40wt oil such as M1 0w40 or Rotella synthetic 5w40. Turning higher than stock redline, you want a little extra cushioning from a thicker oil. Also more heat will be generated from extended times doing this so you'll want a thicker oil that won't break down as soon. What do you have done to your GTP anyway. There's no reason to spin it higher (although it certainly can take it) unless you have a bigger cam or at least stiffer springs but even then you wouldn't make any more power up there since the valves stay open just as long as stock. Jason
 

Will

Thread starter
Messages
26
Location
Toronto ON
thanks for the suggestions guys, please keep them coming! I'm also in agreeance on having a slightly thicker oil than 10W30, slightly being key word. Does 15W50 Mobil 1 SS have moly whereas the 10W30 doesn't, different additive package? Also Patman thanks for the Castrol recommendation. Here's when you've been hiding! I remember seeing your name around the OQCGP community when I was just getting started. Do you have any UOAs that compare Castrol Syntec to Mobil 1 as a generality? It sounds like between the two, I shouldn't really bother with Redline, just stick to one or the other from Wallymart and change it nice and often. Question is which one to go for? [Eek!] No problem on the razzing guys [Cheers!] [Big Grin] I'm running a cam and ported heads with upgraded valvesprings and retainers, my GTP is NOT stock but I am new to the world of overredlining :)The motor is basically set up for this valvetrain wise however not much can be done with these oil pumps, its a rather unique design that's hard to work with. I want it to be well protected though so I'll use the best oil based on what's recommended by those who know. Again, those who run GTPs with 6500rpm shift points (which are few) say that they run 10W30 (won't name a brand though) and change it regularly, they are also daily driven cars. Also if anyone has suggestions on ATF, I have a thread going in that forum but very few responses [Frown] I've been told B&M Synthetic Trick Shift (the new one) is slightly thicker than normal ATF to high rpm use, was the guy in Karbelt talking out his *** ?
 
Messages
453
Location
Galveston, TX
quote:
Originally posted by Will: Hey everyone. Looking for some advice. I own a 1998 Grand Prix GTP, 3.8 S/C engine (iron block). We redline at 6000, determined by our oil pressure I assume, and I want to spin my engine a little past that to say 6300-6500. Our engine is rated for 10W30 oil. People spinning to these rpms currently have said they simply use a good 10w30 synthetic and change it often. I was wondering if I would be wise to use a slightly thicker oil so that it clings a little better to the crank and cylinder walls? Does anyone have experience with this scenerio? Also at the moment I keep switching between Castrol Syntec and Mobil 1, I can't decide which I like better. Mobil 1 seems to be a favorite on this board. I've also been thinking of trying Redline, I don't mind paying for a good oil. Any recommended brands are also appreciated. thanks!!
As a kid, I used to be part of a cult that raced Honda 4-cylinder air-cooled motorcycles(4-stroke OHC engines). Those Honda's were Wild Thangs!!!! We'd take the tacho needle in one end of the redline band, and out the other end. Rpm's, about 10,500 to 11,500. Some boys had special custom crankshaft with racing Con Rods, they operated theirs at 13,500 rpm. Castrol 20w-50 mineral was one oil that we used. Castrol monograde straight HD-30 was another oil. Some people were able to get their hands on synthetic oil in 20w-50. But if you want to run your machine at where the Tacho needle is pegged, I would not expect the same Machine to live forever, whatever the oil selected for use.
 

J

Messages
434
Location
Berkeley
quote:
Originally posted by Will: Does 15W50 Mobil 1 SS have moly whereas the 10W30 doesn't, different additive package? Do you have any UOAs that compare Castrol Syntec to Mobil 1 as a generality?
Hi, All grades of Mobil 1 have moly, but 15W-50 has an additive package comparable to that of a good diesel oil such as Delvac 1. The following is an image from earlier thread:  - Be careful with Castrol Syntec 0W-30. It has to say "Made in Germany" or it's no good. [Cheers!] And oh ... I almost forgot ... [crushedcar] Jae [ April 05, 2003, 07:29 PM: Message edited by: J ]
 

Patman

Staff member
Messages
22,017
Location
Guelph, Ontario
quote:
Originally posted by Will: Also Patman thanks for the Castrol recommendation. Here's when you've been hiding! I remember seeing your name around the OQCGP community when I was just getting started. Do you have any UOAs that compare Castrol Syntec to Mobil 1 as a generality?
I just posted a UOA in my sister's 99 Civic using Mobil 1 5w30 for a 13,000km interval, and now she's running the 0w30 Castrol, so in a few months I'll have data on that. Although the Mobil 1 interval went through the winter, so it's not a 100% fair comparison (winter degrades the oil faster and causes higher wear numbers too) Be sure to say hi to all the guys in the OQCGP club for me!
 
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