Who is running royal purple motor oil. I just put it my vette and was told it would make my engine leak, Is this true?

 

Its one of those old wives tales about synthetic oil in general...that is "causes" leaks. If you notice any leakage after switching to it, it is due to the fact that it has more of a detergent effect than conventional oil, and will help clean out some of the deposits that may be lodged in the gasket material. So, if the gaskets are old and in bad shape, then yes, you may see some leakage. If not, don't worry about it. That said, if you have a flat tappet cam (not a roller), I would switch to a conventional oil that has the additives in it for a flat tappet cam. This would include most of the conventional racing oils, diesel truck oils (Delo, etc), and a few other off-road type oils. The newer oils don't have the additives needed to protect a flat tappet cam.

 

Thanks for the info.

 

Hate to sound ignorant--what is a flat tappet cam and why would that make any difference. I have solid lifters with the original cam and run Royal purple and have had no problem. Please explain?????

 

Zinc content has something to do with the fact you use dino oil (with high zinc) instead of synthetic in flat tappet engines. Why?... not quite sure,,maybe someone can shed some light...

 

You may never have a problem, but lots of people have. I do question how much of it is due to improper breakin, though.
Any cam that uses a "flat"-actually slightly concave- bottomed lifter is a flat tappet cam. This would include any of the factory style cams found in all Vettes up until the later C4 years (around 86-87), whether hydraulic (L-79, L-82, etc) or solid (LT-1). As opposed to hydraulic roller cams, which have been found in all factory passenger car small blocks (to include 92-up LT1 and 97-up LS motors) since the mid to late 80s. Hydraulic roller lifters are similar to the flat tappet lifters in the way they work, but they have a small wheel pinned to the bottom that actually makes contact with the cam lobe, rather than the lifter bottom itself spinning on the lobe. They also have guides that the lifters ride in (they look like a figure 8 sort of, commonly called "dogbones", and they are held down to the lifter valley by a sheetmetal brace (secured by bolts in the lifter valley) often called a "spider".

Because of the increased friction, the flat tappets are more sensitive to lubrication, and need oil with plenty of zinc additive to live. Due to emission requirements, most of the zinc has been removed from current passenger car formulated motor oil. This leaves a few choices...use a motor oil intended for big diesel truckslike Delo or Rotella- they still have the additives, but may not for much longer-; run a racing formula motor oil; run the specialty oil that someone is having blended to combat this problem (someone please chime in, its been posted here before but I don't have the info); or switch to a hydraulic or solid roller cam. Hydraulic rollers are much more expensive (most cam companies sell a "retrofit" hydraulic roller for older engines), unless you are building a new engine and use a later block already set up for it (taller lifter bores, drilled valley, cam retainer plate). They do last longer, offer more agressive profiles, and are easier to break in-just cover the lobes with motor oil, put some assembly lube on the journals, stick it in and run it. Solid rollers have similar advantages, but have a higher RPM range (lighter lifters),cost much more (no factory-based parts), and dont do well on the street (they are made for higher RPM ranges; extended idling will often kill the lifters, and the profiles are usually very aggressive and require stiffer valve springs-causing more maintenance).

 

I swapped mine over with 150,000 miles on her, R/P 5W40, no leaks. i did change the pan gasket to a new one peice and the front cover gasket at the time though.

 

Posts like yours make me believe that the cam lubrication issue may actually be more poor break-in technique, or shoddy heat treating on newer cams and lifters, than the amount of zinc in the oil. How many miles since you switched to synthetic? Is it the regular stuff, or the race oil?

 

It's the regular, the XP stuff is probably better, it'll go in on the next change. I'm not running a flat tappet cam though, they say that the reduced zinc in the reformulated oils is leading to the cam failures, the XP has high zinc in it, so it should be good for that application. no leaks.
Send my your e-mail and I'll send you an oil test I got on PDF, real eye opener for those running Mobile one.

 

That is a very insightful post and certainly one of the best I have read on this often misunderstood subject

 

I mix dino with high zinc with RP regular 10W-30. No leaks.

 

I broke mine in with Castrol GTX then once I hit the 2,000 mile mark I switched over to Synthetic n now 2,500 miles later all is ok no leaks at all.....As long as she is broken in properly you should be ok.......Jerrylee///

 

i know it's just a typo, but a flat tappet with concave bottom will be worn out; when new it will be convex. the convex shaped tappet mated to a lobe cut on a slight angle will provide a contact patch slightly off the centerline of the lifter causing it to spin . . .

 

I wouldn't put it in anything. I swear by the Joe Gibbs Racing oils, and they now have a "Hot Rod" series street oil