My paint on my new 1996 XJS is in good overall condition but needs some TLC.
In the past I have used Meguiar's Ultimate after just a good wash and have been happy with the result.
Will it really make a difference if I clay the car before compounding? It seems to me that the compound should do the job of removing contaminates without bothering with the clay.

 

Pete,

I also use Meguiar's Ultimate but always clay first.

A thorough wash and then use clay bar before compounding.

Clay lifts contaminants off the paint - especially the microparticles stuck to the surface that even the most fastidious washing won't remove. There is no abrasion in this process.

Compounding, however mild the product, is actually removing clearcoat to achieve the scratch and swirl free shine. If the microparticles haven't first been removed with clay, they will be loosened and mixed in with the compounding product. You will achieve the same shine in the end but at the cost of removing fractionally more clearcoat each time than strictly necessary.

If you've never used clay before, the difference will amaze you. Running a finger over a freshly washed panel and then over a washed panel that has subsequently been clayed is the best possible demonstration of how effectively it cleans.

Graham