I live in the UK and I want to use the correct oil for my 1999 Z28 and not get ripped off.

The manual recommends 5W30
The garage that I bought the car from recommends Mobil 1 0W40.
The Corvette dealer that last service the car used Nascar 76 10-30
I have a friend that works for Ford and can get a discount on 5W50

I have been told that the Ford oil is very good but will it be any good for my Z28?

 

M1 oils tend to be thin for their weight, so yeah 0w-40 should be fine. Can you get the German Castrol out there? If so, that's supposed to be the best oil for our engines, but M1 0w-40 is a good alternative too. What ever you do, don't go w/50 weight, wouldn't even run that out here in the desert of West Texas.

 

I wouldn't use a single viscosity oil. You need something that can adapt to temprature changes... Just my opinion.

Castrol is good oil. I use a mix of Syntec 10w30 and two qts 20/50 to eliminate that start-up piston slap noise. Pluss it get's pretty hot out in NM.

I used MObil 1 and thought it was a bit thin.

Generaly oil is oil, but synthetic offers a bit of protection when the temps get up there.

 

Thanks, I think I will go back to M1 0W40, it has got Nascar 76 10-30 at the moment and last winter it seemed to be a bit noisey (tappet sort of sound) for the first few seconds in the mornings, I guess the oil was taking time to get to up there.

 

That's why I used the 2 qts of 20w50 w/ the 10w30... The piston slap noise, or just dry lifters.

 

Not sure about 2 qts of 20w50 w/ the 10w30, angel71rs says don't go w/50 weight. Mobil 1 0W40 is what I have used before but my friend at the Ford garage says Ford 5W-40 is very good and he can get 25% discount. I am happy to pay a little more to protect the motor so of the two which do you think is the better option, M1?

Another question, fully synthetic oil means you don't have to change oil so often, should be OK for 10,000 miles, but the filter should be changed more often. How can you change the filter without draining the oil or should the filter be OK 10,000 miles as well?

 

Bayer is mixing in some 50 weight to help quiet some engine noise. I think this is a mistake. Thicker oil will quiet piston slap, but it also makes it harder for oil to flow at startup. Most engine wear occurs at start up b4 oil gets to what it is supposed to be protecting.

That is the beauty of a good synth like 0w-30 German Castrol or 0w-40 Mobil 1. It flows quickly when cold (0w), but it protects much better than dino oil at operating temperature and under load. BTW, since M1 oils tend to be thin for their weight, 40 weight M1 is roughly equivalent to 30 weight GC.

50 weights are sometimes used on racing engines that experience severe sustained loads, and that use looser bearing clearances. These engines get rebuilt after only running a fraction of the miles a street engine is expected to see. They really don't care about startup wear.

Modern engines like the LS1 use tighter clearances, so using a thicker oil is detrimental IMO.

Piston slap (that ticking noise you are probably referring to at startup) is sometimes present on LS1 engines. It has no ill effect on engine longevity. It is a result of GM no longer using the steel slipper skirt in the pistons that were used in the classic small block Chevy pistons. The steel slipper meant the pistonss didn't expand as much when at operating temperature. Not using it meant GM had to increase piston to bore clearance to allow for extra expansion on LS1 pistons. With variations in machining tolerances, if an engine with pistons on the small side of allowable tolerance were installed in a block with bores on the large end of allowable tolerance, the result was more clearance... and piston slap when cold. But GM had to do this so engines with pistons at the max limit installed in blocks with the min limit wouldn't seize up/gall the cylinder walls. The 97 LS1 was the guinea pig for the use of these slipperless/short skirt pistons in a production engine, they got better at it as the years passed.

Slap is also due to the use of a much shorter piston skirt. Both of these changes resulted in much lighter pistons and contribute to the quick revving we so enjoy from these engines.

Neither of the LS1s I've owned had/has piston slap. But if one did, and I had to choose between using thicker oil to quiet the slap, and compromising startup protection, or using a thinner oil that afforded better startup protection and just accepting the slap, I'd use the thinner oil. No doubt on that. Again JMO.

As far as changing just the filter, sure you can do it without draining the sump, you will only lose the oil in the filter and what runs out of the oil passages above the filter. Recommend you use the long type "truck" filter for added filter area. Especially good are the Mobil 1 filter, M1-206, and the K&N filter, hp2006. You will find this long term study of synth oils on an LS1 informative, and might help you decide if changing the filter is necessary before 10k/miles:
http://neptune.spacebears.com/cars/s.../oil-life.html

 

Thanks, The guys realy did some very good testing.
After that I will try the Mobil 1 filter, M1-206 but I am not sure weather to stick with Mobil 1 0W40 or change to 5W30, the report clearly shows that going to 40 is too thick, may cause rought running and lower MPG