Oil Viscosity? What's Best

jams · #1 (**permalink**) 10-23-2002, 10:08 AM

Hi Guys,

I was wondering what oil viscosity most of you use. Do you use what the manufacturer or rebuilder recommends? I am sure this is a topic that has many different answers. I currently have a crate motor (330hp) and I am using the manufactures recommended viscosity.

Thanks
Jim

Jeff Frigo · #2 (**permalink**) 10-23-2002, 11:20 AM

Stick with what the manufaturer or builder says. Bearing clearances are different from engine to engine. After you break your engine in (around 1,000 miles), you can change to a synthetic if you want. Will pick up 10-15 hp.

Cobra #42 · #3 (**permalink**) 10-23-2002, 02:23 PM

As Jeff said, don't use synthetic oil until after break end period at least one thousand miles or 15/20 hours of running , not just idle but running time , like on a dyno while tuning.

Back in Black · #4 (**permalink**) 10-23-2002, 02:50 PM

I plan to go a bit further...maybe 2,500 to 3,000 miles on 20/50 Castrol or similar.

Some in the know like to test for compression...when it tops off and no longer increases...then the rings are set and you can switch to synthetic...Mobil 1 is a good readily available synthetic of very high quality. I plan to use a custom blend of different weight Royal Purple synthetic..since they don't make a multi-vis with the heavier weights I want. (about 5/20/40/50)

Maybe more important is the oil FILTER...never use a Fram...they are very restrictive, especially at start-up.... Mobil 1, or K & N would be my top choices in a filter...but there are others also..there is a very good thread on this (oil and filters) in the archives.

I went with K & N because it was good, and the black matches my SVO 514 block

Jack21 · #5 (**permalink**) 10-23-2002, 03:44 PM

10W30 for a tight engine, 10W40 for a loose engine. Use synthetic after engine is broken in.

Mr.Fixit · #6 (**permalink**) 10-23-2002, 03:49 PM

I run the lightest oil my engine still maintains acceptable pressure with when it gets hot. Depending on summer or winter, long freeway cruising or around town. So it gets between 5w-20 on the light end to 20w-50 during the summer. Just keep the oil warm, yellow, and run a WIX racing oil filter.

Bob In Ct · #7 (**permalink**) 10-23-2002, 04:51 PM

Hey Jim:
Keep in mind that heavier viscosities (20W-50) give poor start up lubrication, reduce power and do not easily get through the extra hoses and oil cooler most Cobras have.

I run 5W-30 Mobil1 and my pressure never goes below 50PSI (351 Crate). I would not be custom blending straight weight oils, 2 quarts of 10 weight, plus 2 quarts of 20, plus 2 quarts of 30 does not produce 10W-30! Do not use the Fram filters, use Wix or Mobil1.

Bob

Lubrecon · #8 (**permalink**) 10-23-2002, 06:59 PM

Just so everyone knows, Corvette, Porsche, and Vipers all have Mobil 1 as the initial fill from the factory. The "don't use synthetic until the engine is broken in" is an old myth. Many other eurpoean cars, Mercedes included use Mobil 1 as IF. Most builders have no clue about lubrication. Not trying to be cute, but have 35+ years in the field of lubrication. Mobil 1 is the best there is. However, the reduction of ZDDP is of some concern, but that is industry wide. The motorcycle version has more ZDDP.

Back in Black · #9 (**permalink**) 10-23-2002, 07:25 PM

Please provide them to prove to us this here-to-fore unheard truth ?

Until I see proof, I see no problem with playing it safe and allowing my motor to break in with standard oil.

STROKER · #10 (**permalink**) 10-23-2002, 07:28 PM

Lubrecon,

I saw this thread and figured I would find you somewhere in here.

When are you planning on installing brakes? David's up here in the hill's but I haven't had a chance to talk to him yet.

Danny

Lubrecon · #11 (**permalink**) 10-24-2002, 06:45 AM

Stroker:

I sent you an email, did you take a look? Tell David to knock it off with Bambi and get back here so we can get the suspension and the brakes installed. Yeah, couldn't resist to comment on this topic. The old wives are still around, at least their tales.

Put up some pics of that bad boy and let's see what the master builders(the Mustang guy too)have built. Is it rolling yet??

Jerry

cobrashoch · #12 (**permalink**) 10-24-2002, 07:39 AM

Lubrecon - I disagree. It depends on the rings you are using on the break in of a fresh engine and the clearances you use. If you are using molly rings you are right, you can use synthetics most times though. A couple of years back I built a "tight" engine using stock iron parts and broke it in with Moble1 and it broke in so funny(weird) that I tore it apart after 700 miles to see what was going on. (it had blowby and compression issues) Nothing wrong, I put it back with 20w straight weight mineral oil. After about 30 mins. of use later it started to come around. As for the type of oil to use after a break in, I usially tell most folks with street cars like Cobras that Red Line followed by Moble1 is the way to go. I'm a drag racer so I use Royal Purple of course. With a new "loose" drag motor you can almost use anything you have sitting around to my way of thinking though. As for ZDDP, the more stuff you throw into oil the yukkier the oil change is when that stuff wears out. With less stuff in there the more you have to change the oil, like what the manufacturer recomends- imagine that! Motorcycles have wet clutches a lot of times and I think thats the logic there of more friction additives because a lot of times M/C manufacturers tell you NOT to run synthetics because of wet clutches. In fact I knew of one bike a couple of years ago that synthetics would void the warranty, and I'm not a bike guy.
cobrashock

Dave V · #13 (**permalink**) 10-24-2002, 08:45 AM

I have a 390 FE with about 9K miles on it. Last spring I changed the oil from 10-30 to 20-50. This summer I started seeing both hotter oil temperatures and some variance in the oil pressure. The water temperature has stayed OK, but the oil temp will be up to 30 degrees C higher than the water.

After reading this thread I am wondering if I shouldn't be running lighter oil, 10-30 or 10-40. Any recommendations?

Dave V

Back in Black · #14 (**permalink**) 10-24-2002, 09:02 AM

After the 3,000 mile break in period...and have 1,000 more miles now...no (wet) clutch problems... this supposed "wet clutch" slippage with synthetic oils may depend on what materials are used in a specific clutch. Mine seems fine...but I don't drag race it either, maybe it would give out sooner with synthetic...don't know.

Lubrecon: Where's the beef?

Cobra #42 · #15 (**permalink**) 10-24-2002, 12:01 PM

Lubercon, You are correct in stating that Corvette, Viper and other things come with Mobil 1 when shipped to the dealer. But.... check what the engine are first run on at the factory..... it ain't Mobil One

cobra fever · #16 (**permalink**) 10-24-2002, 01:54 PM

what you guys think about the Fram hp1 racing filter? I was running 10-40w motor oil for the first 800miles then changed to 20-50valvoline vr racing. I change the oil every 500 miles, and fill the tank with atleast 5gallons of racing fuel call me crazy. The other thing I learned is that lot of the guys who are attending racing events, are changing their oil from 20-50 to heavier weight 10-40 or 10-50. Got to ask my engine builder when to change to
synthentic

sharpel · #17 (**permalink**) 10-24-2002, 03:45 PM

I have never thought about it until now, changing to synthetic oil that is, but after reading these threads I am interested. I still have a fresh motor, about 600 miles on my 351W with 435hp, and switching to synthetic was never a consideration.... until now. Is it really that much better, and does it really give you more horsepower!?! I am far from being an expert on this issue but now I am interested in learning more. Any help?

Mr.Fixit · #18 (**permalink**) 10-24-2002, 04:01 PM

Forget about picking up 20 horsepower by changing motor oil, even if you do, it would take a racetrack and timing equipment to notice the difference. Pretty much everybody I have ever spoke with is in agreement that synthetic is far superior to mineral oil as an engine lubricant. If you can afford it, use it. It will find a way to leak out of an otherwise leak free motor however. I am not a PhD in lubricative technologies, but I would still do the first 1000 miles on non-detergent mineral oil, just like the old days. Maybe it's just superstition. But your motor would probubly prefer you take it relatively easy for the first few miles anyway, so having slightly inferior oil (mineral oil) in for those miles won't hurt you. Never tried breaking in a motor with synthetic, so I can't say if it works as well or not. But to me, the risk of poor ring seal vs. the difference in engine wear because I used mineral oil for 1000 miles is a no brainer, I need my rings to seal, and these motors run a long time on mineral oil (maybe longer on synthetic), but the loss of engine life because I used mineral oil for 1000 miles should be nonexistant.

Lubrecon · #19 (**permalink**) 10-24-2002, 07:21 PM

Let me address each in order. Cobrashoch: Rings respond to viscosity, regardless of the oil's basestock. The major benefits of a Mobil 1 are low temp pumpability, quicker upper engine lubrication at start up(start up wear is 80% of all engine wear), greater resistance to oxidation(very valuable in high HP engines), reduced wear associated with boundary lubrication, extended oil life, greater dispersant capacility(read cleaner engine over time), very high viscosity index(less reduction in viscosity as oil temp increases), stay in grade multivis, and many more. You will note that lubricity is not a significant benefit over mineral oils, there is some however, but not much, the coeficient of friction is similar. Without ZDDP, your camshaft would be toast in no time flat(no pun intended). For your info, while other antiwear additives have been used in motor oils, ZDDP is the most cost effective. In fact, the industry is in an uproar at present over the proposed reduction of ZDDP(or zinc in particular) for the forthcoming GF-4 spec. The problem is backward compatability with older engines, and a real concern. The reduction in ZDDP is aimed at reducing catalyst fouling, not to get you you to change your oil sooner. Additionally, ZDDP is an anti-oxidation additive that reduces the amount of yucky things in your oil when you change it. The oil utilized in the wet clutches of motorcycles it there to cool the clutches, not lubricate anything, so actually any Mobil 1 type of oil(PAO) would work just fine.

Cobra #42: What do you think the term Initial Fill means? I don't know, but why would a GM, or any other manufacturer run an engine and then completely change the entire oil charge out, just to turnaround and recommend something else? What a waste of oil, anyway, the car companies do not break in engines before they ship. There is no longer a break in period as we used to know it.

Sorry guys, still an old wives tale.

Lubrecon · #20 (**permalink**) 10-24-2002, 07:28 PM

Sorry, Mr. Fixit, I did not see your post before I started my diatribe. You may be able to buy a non-detergent motor oil from some backyard blender, but not from ANY major supplier of engine oils today. The spec has been obsolete for years and you should never use a non-derterget oil and any engine for any reason other than to screw it up big time. That includes "break in" or whatever.