Oil type

[Hamish Coutts]

Dynosaur or Synthetic oil that is the question.

Reading posts including replies to my own query, recently, there are varying opinions to the best type of oil to use.

Keith - "This is exactly where the synthetic oil kicks the dinosaur stuff's butt." do I take it that you use synthetic? If so who's?

Any opinions what's best for general road use with the odd outing to play on a track. I'm hopefully, just about to rebuild my engine, so this seems a good point to decide the best oil to use.

Regards,

Hamish.

[poiuyt]

I use Mobil One full synthetic in every engine I have: the GTI VR6, the Elan, the Fiat X1/9, the Honda and Kawasaki motorcycles and even the lawnmower and the edger. Oh, yeah - in the bikes I use Mobil XGT4, which is full synthetic made for motorcycles that share the crankcase oil with the clutch - don't use the regular or you could be looking at a slipping clutch.

After losing two engines (one GM and one domestic Ford) to sludge, nothing else goes into the engines. In the Elan (1969) I use 15W50 most of the year and 10W30 in the winter, if the car is used at all in the cold.

Some of the "synthetic" oils are not fuly synthetic and use the dino juice. There are other full synthetics but I'm not sure which they are (and there is a Mobil that is part synthetic, so read the labels.)

My GTI will hit 190,000 miles today and everything except the starter and the fan belt idler pulley is original.

Steve Becker
1969 Elan S4 DHC
1978 Fiat X1/9
1996 VW GTI VR6
1992 Honda Nighthawk 750

My wife has a 2000 VW GTI Turbo and the 2001 Kawasaki Vulcan 750, both of which run Mobil One as well.

[twincamman]

wellll I once had a 20 minute chat with an engineer from valvoline about this subject during an event at mosport---asked the same questions you do ---should I use it --what properties --viscosity's--etc etc ----his final reply was ----'son--there aint nothing slipperier than oil' -------and I have always used it but 3 years ago I thought after 10 years they must have made vast improvements and decided to treat my 150000 mile motor to it after the next rebuild----result---number 3 con rod bearing spun --cost 900 bucks to have it spray welded back to standard size ----I would not use that synthetic stuff in my lawn mower -- the word SYNTHETIC says it all ---ed

[M100]

>twincamman-number 3 con rod bearing spun

But, unless you can convince me otherwise, that is realistically nothing to do with the choice of oil and would be down to one or more of the following:

the con rod big end housing size
the od and id of the big end bearings
preload / integrity of the con rod bolts

Having seen the insides of an (albeit 90's Elan) engine with 200k+ miles on it where you could still see the cylinder hone mark and the main and big end shells were perfectly reusable I'd never use anything but synthetic apart from initial engine run in.

The twin cam from my Sprint was rebuilt over 15 years ago and has now done around 50k miles since on synthetic. The main and big ends visually checked just a few weeks ago are as new.

If properly built with parts in good condition and not hacked around by a DPO the twin cam could quite easily be reliable for a good 100k miles or more between rebuilds running on synthetic. Given the rarity/cost of cranks, pistons and blocks its a total non brainer to run with it.

[steveww]

I used Castrol Magnatec which is semi-synthetic. Happy sitting on the fence

[chrishewett]

The guy that looks after the engine on my brothers 5litre TVR claims that if you use Mobile one it is so good you need never change the oil again, just the filter! He may not mean this literally but he is a can-am expert and is chief mechanic for a race team so I assume he knows what he is talking about. The only thing that worries me is whether synthetic is suitable for an old engine like the twincam.
Any thoughts?
Chris

[marcfuller]

In the vein of talking to some guy - Yesterday, while seeking a better Elan TC canister oil filter, I was talking to a representative of an OEM German filter maker who mentioned that some older spec filter media has had problems (looses its integrity and begins to disperse) in long term (longer than 3K) contact with synth automotive oil. Not sure how recent this "observation" is and I am seeking more info on this. Anyone else ever hear of this?

[twincamman]

ouch---hacked around-----no the engine was finished by my engine builder I was unable to finish the rebuild as another commitment prevented it --and he is good------------ Valise motor sport --f2000 ff1600--vintage and vee motors --the motor is now on the 180000mile trip --ed

[chrishewett]

What???

[twincamman]

the motor was assembled properly------ed

[M100]

Ed>"the motor was assembled properly"

If thats the case then I really, really struggle to understand the mode of failure. I'd certainly not be blaming the choice of oil and be more concerned about torque wrench calibration, big end ovality and the like.

[twincamman]

well I dont-- wont --use it --as I said SYNTHETIC says it all----I dont believe its good for old engines --[and its my 160000 mile motor] --and the only bearing faiure was with that stuff -----ed