007rollie

I have ran MOBIL 1 20-50 in several C4 Corvettes that I have owned in the past. Is this to heavy for LS1 ENGINE? Anyone running 20-50 in there C 5 ?

screw991le

Kinda thick?

silverz06vette

LPE and other tuners say to if you are modded like a H/C package.

Mobil 1 5/10w-30 or any other good oil (amsoil, redline) will do just fine in your C5.

15w-50 does not flow that well when its cold out, so for cold starts in the winter I would not use it at all.

GUSTO14

It certainly isn't gonna hurt anything, but it will probably cost you a few horsepower...

Unless you have a very loose engine, I can't imagine why you'd want to run this heavy an oil. But again, it isn't gonna hurt anything.

GUSTO

eddie44

Unlike most here on the Forum I run 10w-30 in mine but I'm in 115 degree heat right now. I think it thins out in that kinda of temps. Not sure I'd run something as thick as 20w-50. As someone else said I'd be afraid of cold starts.

GrayC5

Certainly not recommended by the Owners Manual and the GM Service Manual. My '03 Owner's Manual and Service Manual specifically state not to use SAE 20W-50. Only recommended viscosity is SAE 5W-30 in a synthetic that meets GM Standard 4718M. The Mobil 1 synthetic 5W-30 used to fill the C5 engines at the factory meets this standard. The Owner's Manual says you may substitute SAE 10W-30 when the temperature is expected to remain above 0 degrees F and the 5W-30 is not available. You should see your Owner's Manual for more details.

Dave68

5W-30, 0W-30, or 0W-40 are the only oil viscosities I'd use. 20W-50 may very well cause premature engine wear due to its poor flow characteristics at startup temps.

Tom73

You sure? Most engine wear occures at start-up so running a thick mud like that will cause it to take longer to get the oil to the critical parts.

tom...

7.0sc SuperVette

I have been running Castrol 5W-50 synthetic (GM4718M approved) in my LS1/2 engines under the assumption that under cold start conditions it will act like a 5W oil viscosity and at high oil temps it will act like oil in the 30 to 50 viscosity range depending on temperature.

I do this based on what I have seen in the "literature" about maintaining oil pressure/flow at high temps with racing bearing and piston clearances.

This is a belief that I hold and not anything that I have done engineering tests on and the relative few "racing" type engines that I have built or more recently have had built have neither proven nor disproven my belief.

I would be interested in hearing Forum folk input on this.

May the BOOST be with you!

Roy

AU N EGL

The heavey weight oils are for running in consistantly hot envornments. Road racing or track days where oil temp is 240* and above.

I also use an oil cooler and keep my oil temp 250-255* even on the hottest of days or the hardest of runs.

I use 15w-50

jimcork1

I used it in my Lincolns and drove them for 150,000 miles. Engines were in great shape when I sold them. Now I don't live where it gets below 20 F and the summers are easily 100 F. The lincolns were garaged at 60 minimum temp. So oil flow was not a problem. If you live in N Dakota I would not use the 20 50. If you have it in your car now it won't be much of an issue and might cost you 2 hp. I would not drain it just to change viscosity. So really it is your choice I don't think it will affect engine life if you live in the south,, but up north in winter might have some affect on a cold soaked motor. Just my $.02

99 Nassau Blue

Bill Curlee

Dude

You need to run 5-30 or 10-30 and forget about the race stuff!! Some times MORE is NOT better!

I live in the north east and run 5-30 in the winter and 10 -30 in the summer!

BC

davidp

I had LPE do a Heads and Cam package on my 03 ZO6. It included upgrading the oil pump, push rods and stands, timing chain, headers, x pipe etc. Their quote in the service instructions provided with all engine modifications from LPE is "During the summer months we recommend Mobil 1, 15W50 weight oil and during the colder months we recommend 10W30. The recommended period for oil change is every 3000 miles or 3 months which ever is sooner." If you prime the oil filter when changing the oil, upon startup there is plenty of oil available for proper lubrication. At idle I hold 80lbs of OP cold 70lbs with the oil at 198-210 degrees. It does not get hotter than that due to 160 thermostat and reprogramming of the fan motors. I do not get into the throttle until the oil has reached 190 again as recommended by LPE FWIW

GUSTO14

Tom,

Synthetic oil flows so well hot or cold, you would be hard pressed to detect a difference. I've spilled 90 weight synthetic gear oil on the garage floor and it flowed like 10w-30 motor oil. Put some in your freezer and see how "thick" it gets... you will be very surprised... and impressed.

I do agree with most everyone else, there is little reason to run a 20w-50 synthetic.

GUSTO

AU N EGL

with GUSTO

I also use a 3 qt accu-sump to prelub the engine for 60 sec before cranking it over.

Dave68

Gusto,

I spoke to a Mobil 1 applications/technical help person not too long ago. He told me that Mobil's testing has shown that startup wear occurs to a greater extent with synthetic oil weights higher than 5W, even at 70F startup temps. For this reason, he recommends nothing higher than 5W oils for every application except racing. In fact, the applications engineer lives in Texas and is using 0W-40 Mobil 1 in his car.

You may not be able to see a difference by the way the various oils pour, but engine wear does occur more rapidly when using the higher-grade stuff. Racers aren't concerned about getting 200,000 miles out of their engines. Short-term durability at super-high oil temperatures is their priority.

LRD VDR

How hot does it get in KY?

Here in Texas(Dallas) even Satan does not want to be here so I run 15w-50 Mobil 1 or RP 41 or even 51 when I do track events and I have Oil and Tranny coolers.

Shahram

b98

Same here I run 15/50 , it's not 50 when the oil is cold. And the word cold is not in the Texas redneck dictionary.

loudsam

I run 15w-50 in my LPE heads/cam '99 coupe. That's what Lingenfelter said to run in it.

AmericanPie

I just thought I'd point out that for my 1985 635CSi, BMW recommends 20W-50 from 15 to 120 degrees F. They only specify the lighter weight stuff (5W-20, 5W-30) up to about 20 degrees F. I know comparing the BMW M30 inline six to an LS-1 is like apples to oranges, but BMW motors aren't exactly known for having "loose clearances". And many BMW guys, using factory-specified oil viscosity, are getting well over a quarter million miles (some even over 500,000) before lower-end rebuild time. Most I know (including myself) are using synthetics.