XJS and Winter

[extratime1983]

Hi all,

I've had my 1994 XJS now for 3 months and all is going well. I've sorted out my transmission worry (as per my discussion in the transmission forum).

Owning an XJS is something i've been after for a very long time and now I have one, I am keen to keep it in the stunning condition it is in.

So this leads me onto winter driving (automatic, rear wheel drive) . No, my concern more is treating the underbody. From experience gained by fellow XJS owners, should I be investing in treating the underbody?

I know the older XJ-S models suffered from corrosion on the underbody, but the facelift models appear to be better treated when it comes to the underbody.

[att]

I will second this motion.........
Seriously, it would be nice to have some experience and sound advice on this one....

[milly2]

I had mine done in May by Clarkes.
They did a good job and I got to see the museum and as many xjs' as you could hope for.

It certainly wont do any harm having it done and it gives you a chance to check out the state of the car underneath

I am sure there will be seasoned forum users that can advise how to do it yourself.
Milly

[almcl]

My experience with a facelift is that while the underbody is better protected, it isn't perfectly so.

I bought mine a few years ago with only 24,000 miles and had it re-undersealed by the garage that had looked after it for most of its life. It still managed to develop some rust holes which I have since repaired with a welding torch without too much difficulty.

The now double thick layer of undershield was not a great help. While it prevented some damage, when it was perforated it trapped water and similar against the bare metal and concealed the progress of the rust. By contrast, my XJ6 only ever had a layer of paint on its underbody. When this got damaged the rust was evident and could be treated and, as far as I can tell, it didn't perforate any quicker than an undershield protected area would have done.

I suspect this goes against the conventional wisdom, at least amongst the trade.

[kelsham]

I agree, underseal tends to harden and flake off allowing water to be held beneath the edge that is left.
Some years ago I owned a Renault Dauphine, yes I am that old. At this time,I was talking to a girl student from France and the conversation turned to my Dauphine.Hearing that I was concerned with the fact that it rusted faster than an early Vauxhall Victor which was a remarkable achievement, she told me that in France they sprayed the underside each year with old engine oil. This apparently solved the rust problem.

Of course this is probably not green and there is probably a good reason not to do it. I have invested in a small compressor and usually apply waxoyl every couple of years into the box sections. They do a black coloured wax which I spray on the bottom at the same time.

I have been considering adding new engine oil to the mix. I notice that Waxoyl does not penetrate rust in the same way as oil. However oil alone tends to dry out. The hope is the mix will penetrate and stop the oil from drying out.

The best way, regular inspection and repair of the underbody. Regards Kels

[MichaelSB]

When I was a Young grease monkey at a ford garage they offered an annual service to spray the underside of customer cars with OLD engine oil and the results were excellent as the upper bodies were in worse condition than the undersides.

I am sure anyone who has looked under an old car with an oil leak will have noticed the oil trail area has no rust.

Another useful but sometimes messy trick was to poor clean oil down the rain drain holes and inside of door bottoms etc which drips on the floor but gives good protection.

[JAGAZ]

Only problem with the oil treatment these days is that the detergents and other chemicals contained in todays modern oils will eventually remove any underbody teatments that have been applied at the factory .Sod`s law i say.

[Hosier77]

For heavens sake dont spray oil on your car! For a start if it drips on the exhaust you risk a fire, but much more importantly even a small amount of oil dropping on the road when its wet makes it really slippery, which is dangerouse enough to other cars but is deadly to motorcyles (I speak as a proud Triumph owner, i even buy British with my bikes!).
Generally, from the cars i have seen the usual underseals do trap rust in, the only time it is safe to apply them is on a new car or one that has just been completely rebuilt.
The best way I have found to combat rust is keeping the underside in good order, regular inspections and quality repairs.
Although a thin coating of waxoil, applied when the metal is warm, does work very well. But again, a thick coating can trap moisture, so I dont over do it.