Hey guys, I'm approaching 1,000 miles on my new 383. Currentlym I'm using Castrol 5w30 oil for the break in. However, I have a question as to which [synthetic] oil to use once past the break in on my motor?

I searched this forum up and down and read a few interesting posts, but when it all boiled down, there was very little about this specifically for 383s.

Grip had posted about this in advanced tech, but nothing conclusive was mentioned there.

I hear that German-made oils such as 0w40 are good, but do they apply in my case and where would I find such oil?

The weather right now is 1* F, so it gets cold, and about 70-95* F during the summer months. Should I use an oil for each, one for col weather, and another for warm weather, and which type?

 

mobile 1

 

My own shop recommends Quaker State for the break in period but they want me to stay on it.

I've received numerous PMs and emails recommending Mobil 1.

 

I'd use 5w30 in the winter..IMO Royal Purple is my choice. Then in the summer I run 15w40/20w50.

 

Interesting. I have been leaning towards Mobile 1, but I am still not sure about the weight.

I have heard a lot of good thing about RP, but I don't think I have seen it in AutoZone or any similar stores. Who sells it?

 

Ask whoever built your engine what they recommend.

 

Just called, and he recommended to stick with the oil I have in there now (Castrol 5w30) hhmmmm... Grip, do we have the same builder? LOL. Anyway, I told him I want to go synthetic after the break in, around 2000 miles, and he said 5w30 or 10w30 synthetic should be fine and did not mention a specific brand. I will see if I can find Royal Purple locally, but if not I will go with Mobile 1.

 

If you go with Mobil 1 DO NOT use their 5w30. It is way too light. It's actually borderline on being a 5w20 oil. Like anything, there are acceptable ranges of viscosities and Mobil 1 5w30 is on the low side. Now don't take this to mean that it is an inferior oil because it is not, I'm just saying that it's too light for you.

If I were you I'd use Mobil 1 0w40. I used it in my heads/cam car with great success. As a matter of fact after taking it apart and inspecting it (with 138k miles) I can still see crosshatch on the cylinder walls and the bearing wear is light and even. The M1 0w40 is fairly new and I obviously wasn't able to run that exact oil in my car ever since I've bought it, but it has had a steady diet of M1 since the purchase. For the record I did try M1 5w30 one oil change and the oil pressure was low enough to scare me, but stepping up to 10w30 helped out and the 0w40 gave me awesome oil pressure.

 

Mobil 1 here...I've been using the 5w 30 for 10 years...Works fine...Walmart's got it in 5 qt. containers for $20...They have 10w 30 and the 15w 50, too...
--Alan

 

5w30 or 10w30 Synthetic Mobile 1, based on your climate.

Mike

 

The guys recommending 0w-40 or 5-w40 in M1 are doing so based on RESEASRCH that has proven the 30wt. M1s(specifically M1, some brands 30wts are just right) are a little thin for the LT1, not on anecdotal "I used it for 10 years" they have seen the reports of lower wear metal amounts in used oil that is proof. The guys saying" I used it for 10 years" could spin a bearing tomorrow because they have not tested the oil and seen the amount of bearing and block material that is or is not in the oil. Do you trust someone when they say "X" mod was good or do you want too see track times and dyno slips? Oil analysis is how you test wether an oil is good just like you use the strip and dyno for performance mods. http://theoildrop.server101.com/cgi/ultimatebb.cgi

If you are a Castrol man try the Syntec 0w-30 specifically labled "made in Germany" on the back lable, actual lab reports done on used oil are proving that at this time it is the ultimate LT1 oil, good luck finding it, try Autozone.

 

I'm guessing that 96caprice is referring to me about the "10 year" stuff...Anyway, I've used Mobil 1 in a variety of engines from racing to daily driven Hyuandais since the early 90s. Never broken anything. Actually picked up a tenth in my '87 GN. I have no data, definitive tests or lab results. The stuff has worked for me, is readily available, and is relatively inexpensive as far as synthetics go.

John Lingenfelter himself recommended the Mobil 1 5w-30 for my 383 10 years ago and its been running flawlessly for 10 years. I am not trying to change minds here, or convert anyone. I took the advice of someone who had built more LT1s than anyone, period. Use whatever your engine builder feels is right for your combo and you'll be fine.
--Alan

 

Very good post.

 

can't really go wrong with royal purple 5w-30, especially since they sell it at most of the auto stores now

 

GM speced 5w-30 M1 for reasons that have been beaten to death already and absolute longevity was not the key one, Lingenfelter has ties to GM don't think they would like him specing a different oil. Plus it has been 10 years don't you think there have been advances in oil since then, not to mention increased bearing clearances over those years just due to normal wear that will be seen in any engine reguardless of how good the oil is. Maybe M1 was the best oil for the motor 10 years ago FACT is today it is not and it may be a very different oil itself than it was 10 years ago formulas constantly change.

On the Royal Purple from reading some reports it seems too be a decent oil but will not last as long as M1 or some others the Racing formula seems to hold up a little better than the street stuff, in the end probably not worth the hassle of finding and paying more for than you would M1(remember 40wts) or the German Castrol Syntec 0w-30(can be hard to find but is still cheaper than RP).