engine and gearbox oils

paul byrne · Post by **paul byrne** » Mon Oct 16, 2006 4:44 am

I asked Penrite oils why they recommended their classic (monograde?) oils for engines such as the Jup's instead of a multigrade that covers the territory. They said that it was the additives introduced for the specific requirments of multivalves, catalytic converters and emission controls etc that could cause problems in older engines, rather than the multigrade nature. They said that their HPR 40 multigrade (25-70), which is a popular competition choice in older cars in Aus was less likely to be a problem. I am thinking of going with that in the Padman engined Jup. Any comments?

Also what Gear box oil should be used.I tried the HPR 40 but it seemed to make the synchros (2nd gear) worse. Is that due to the miltigrade nature---too thin at gearbox temps?

Keith Andrews · Post by **Keith Andrews** » Mon Oct 16, 2006 7:50 pm

There has also been a movement to remove the Zn fron oils in many countries.
Something that is needed for bedding lifters/cam in Cheviies well on intial fire up, and intial run in.
These Zn oils are still available but for race track purposes only (States)
I wonder if this has any bearing on older classic engines also.

Post by **Forumadmin** » Mon Oct 16, 2006 8:36 pm

I have used additives in my race and rally cars and the humble road vehicles for years. It is difficult to say whether they have had a positive or negative effect, do you blame worn out gearbox washers on the additive or the hard driving? Do you sing the praises of Molyslip when the diff has lasted for 40 years of thrashing or would it have anyway? I believe most of the claims of the additive vendors as over the years the main stream oils have had more and more additives added! Many put Redex upper cylinder lube in the Petrol in the 50s and early 60s before leaded became available. Then STP in the engine and box and Molyslip in the Diff. before all these synthetic oils were here.

Keith Andrews · Post by **Keith Andrews** » Mon Oct 16, 2006 9:53 pm

I am not a fan of aftermarket additives, except for Chevy additive for posi traction diff...if not used it locks.
Modern oils aready contain detergents etc etc, adding more dilutes the lubrication component of the oil.
An extreme example..
I had a dedicated LPG, built in '86...LPG is known for valve resession, "dry fuel" etc etc and the genersal thought was special LPG oils/additives
I never used then, just good old 20/50.
After 140.000 miles and 20 yrs, we pulled down the engine.
The only reason doing so is the car was stolen and thrashed to over 10.000 rpm, ripping 25% of tread off the rear wheels on weelk old tyres.
The right rear cam lobes /lifters and valve springs and rockers where damaged.
Bearings, bores, valve guides, valve seats where as new, other than damged cam etc pieces scoring bearing shells.

Yet other LPG engines at 1/2 the age and milage that used additives showed significant wear on a consistant basis.

In the 1st example above, regular oil/filter changes where carried out regardless of milage at Easter and OCt/Nov

The engines with additives had regular changes as per manufactors recomenations.

If an engine/gearbox/diff is very worn, smokes a bit, high crankcase pressures, low oil pressure (worn bearings) then I belive there is a case for additives.

Keith Andrews · Post by **Keith Andrews** » Tue Oct 17, 2006 12:20 am

Did you not have a rev limiter on your engine to restrict valve bounce?

No...I dont race so no need...normal use and egine design was for 1200 to 5200 rpm thu fully balanced and bottom end etc built for 7500 to 8000 rpm.

If the engine or box is clapped out why waste money on additives.
Do a rebuild

exactly lol...thu while rebuilding replacement engine, gearbox, diff as I am currently doing, its still nice to be able to drive around till ready to swap everything in one hit.

Use SEMI synthetic oil for the engine whch i have not mentioned as yet.

I am not a fan on using sythetic or semi syntetic oils on old technology, pre early 1970s.... ie no Zn.

paul byrne · Post by **paul byrne** » Tue Oct 17, 2006 3:35 am

Thanks Pat for advice on gearbox oil. Box does leak and will until I finish and install the spare box, but I might try the synthetic oil anyway. What would be the effect of non syn 80 gear oil, which is presumably more viscous than the original 30/40 engine oil?

I am fascinated to hear your views on what Penrite said re engine oil!

Keith Clements · Post by **Keith Clements** » Tue Oct 17, 2006 12:50 pm

We will be putting sawdust in them next! Remember those Armstrong dampers fitted to MGAs, the cure for US style suspension was treacle.

Keith Andrews · Post by **Keith Andrews** » Tue Oct 24, 2006 9:48 am

Caution with changing to Synthetic oils on a older engine...
Due to the nature of conventaul oils and there detgents/solvents, over long periods varnish and wall debris can accumilate.
The synthetic and blended oils have different detergrents/solvents, these clean up deposits around gaskets, more than often causing oil leaks.
It is not the oil but old gaskets/time that is the problem.

If changing to Syntetic, ( for an engine over 15,000 miles) keeping in mind the above, it is reconmended to use a pre synthetic oil flush, otherwise these deposts and varnish etc wil be circulating around bearings and such places where they cause damage.

It is reconmended, by the syntetic oil manufactures, and machinists, not to use it for new engine break in....
The general recomenation is to run the 1st 500 miles on conventinal Zn oils (cam breakin) and no additves.
Then drain (which is general practice anyway) replace filter and oil, with Synthetic if you so choose.
It is during this intial stress releif period very fine particals are worn off, usually too fine for filters, and remain in suspenstion, changing the oil removes these...basically a waster of money and expensive oil

Synthetic oil are mainly for high performace/ tubro/ type applications where there is higher potentual for glazing and burnt deposits due to high heat.
It has the advantages of less oil changes....but on the other hand more frequent changes and filter ensures any deposits are removed more frequently.

After weighing up the cost, less maintaince, wear etc there is no advantage in the long to run Synthetics or blends on lower end (less than 6000rpm and 300hp), low milage vehicles....so long as regular maintiance is carried out.

The only differnce between the 2 is the lubricating oil particals are of a consistance size in synthetic and the detergents solvents are different, hence the reason they can be mixed...If mixing your own blends use the same brand names.