Mineral or Synthetic-Based Oils for Older Engines?

[Dolly-Nut]

What's the best for protection (non-turbo engines)? ...ignoring the cost.
Obviously a synthetic doesn't require changing as often, but does it really protect better in an older engine such as a Slant/CVH?

[mahony]

A lot of the guys on here who race sprints use fully synthetic oils so i assume they have better wear protection as synthetic oils do not break down as quick as mineral oils at higher temps, i am going the full synthetic route soon in my engine gearbox and rear axle (penrite as it goes as it has gl4 and it has been confirmed to me by penrite there synthetic oil is ok for a overdrive gearbox )

[Tims Triumph]

Vaolvoline 20W50 is good stuff.

[cliftyhanger]

John Kipping used mobil one in his herald 1500's and swore by the stuff. Not cheap but very good. There are also some excellent 20/60 motorsport based oils. Motul 3000 has been mentioned too.

however, as above I am a valvoline convert. Easy to find at good prices, not too much of a worry if the car leaks a little, change annually at 6000 miles. Job done.

However, the slant may benefit from something a little more modern, especially if thrashed as it should be.

[soe8m]

Another myth solved.

When using a synth oil in a classic it can cause problems. But when it's a newly overhauled classic engine it is much better to use a synth because the synth's are better.

You should not use a synth oil in an old engine because it is too good. It cleans the engine and solves all old mineral residu and that can cause blockage in the oilway's. All the old build up stuff inside the sumpbottom and engine wall solves in the synth oil and that causes the problems. So an old engine keep using mineral and when it's new or did not run much you can use a synth.

Jeroen

[mahony]

Thank's for that info jeroen, will stick to mineral then

[Tims Triumph]

Not sure how true this is (someone will know for sure), but I was led to belive that synthectic oils have can ruin seals and gaskets etc in old engines.

[Jon Tilson]

and the ZDPP?? issue that Jeroen waxed lyrical (and knowldgeable about) recently comes to bear on rebuilt stuff, well cams anyway.

I think there is alot to be said for keeping to the same stuff as you always use.....hard to do as the maker can change the specs...but additive changes can indeed adversely affect rubber seals as Tim suggests.

I stick to more basic oils in older engines. Consumption at sub 1000 miles per pint means its a bit pointless spending out on an oil with a life of 15k miles or more when it only stays in for 6k and is still in grade. Plus our old spec filters need changing at 6k too.

Jonners

[soe8m]

I alway's think in slant. The ZDDP level is in Bardahl 15w50 classic the best. At my work we had 6 "classic" oils tested in a lab and this one was the best and we put in the engines. You can use a synth oil and add ZDDP. In my wife's 2500 i use a synth oil and add ZDDPLUS.

http://www.ebay.co.uk/itm/ZDDPlus-Extre ... 4ac1835c4d

Jeroen