I recently picked up an 83 XJS, with the V-12 in it. My first mission is to give it a complete clean bill of health with all new fluids. I wasn't sure if there were any recomendations or warnings with weights, brands, synthetic versus conventional?


I also have a 98 BMW 740 iL which I have run synthetic in forever, I just wasn't sure if the British cars would hate it or not?


Thanks for any advice!!

 

This is the same as asking which beer is best !

Nothing exotic is *required*. You can run synthetic or conventional.....whatever makes you feel good and helps you sleep at night

I ran my V12 for years using whatever name brand conventional oil was on sale that day. In the 3 months where sub-freezing weather was common I used 10/40. Rest of the year, 20/50.

Cheers
DD

 

viscosity seems pretty agreed upon on this forum and agrees with the manual. Generaly 20w50 if it is how, 10w40 is a good inbetween, or if you can't find 20/50. I've had 0w40 in the winter before and it worked very well, but it is also hard to find.

As far as brand, its not too big of a deal. I've seen a few crappy brands coke up in engines, but also don't want to spend $100 to change the oil.

Lately I've been using the big yellow pennzoil bottles, some research says they are actually really good for the money, compared to castrol and mobil. When I first got my car I put mobil 1 synthetic in it, was like $80 to do an oil change.

Now I get the yellow jugs on sale and do the land rover and jag since they both use weird amounts of oil.

I like synthetic for the mileage between changes, but the uniform molecules seem to leak more on used engines.

If you want the best, the new pennzoil super synthetic stuff they dye to make look like regular motor oil is really good stuff, not counting ridiculous crap like royal purple.

IMO you are better off putting yellow bottle pennzoil in the XJS and changing the filter more often than putting $80 of synthetic in it and changing it every 8-10k miles. No one ever really tests their oil, but often it has a lot more life in it, it is just that the filter gets clogged and stops doing its job. Lately my car seems to do well with a new filter every 6 months and an oil change once a year.

My biggest piece of advice is not to worry about this too much. Tons of people spend a lot of time researching, which is good, but a lot of people get overly-invested. They come to HATE some particular company or think that certain schedules or method or claim that their brand and mileage is the better than anyone else's.

 

With other oils that don't have as many options, like trans and gear oil, don't worry about it much either. There aren't many options, so you could always go for the better one, just know that changing it is better than doing nothing. So many people sit around and speculate about brands being better than others that they forget to change the fluid at all.

the trans fluid seems to work fine in the power steering, but the rear end I think has a LSD modifier, so you may want to check that.

You can take my opinion with a grain of salt, but in a non-ABS car I use DOT5 all day long. The pressure difference is negligible, but most people cry about it. The difference in it not damaging paint and not absorbing any water is massive though. This also greatly decreases the intervals at which you need to change brake fluid. Again, generic prestone dot4 every 2 years is better than doing it every 10, or never, as most people do with brake fluid, but not having to worry about water getting in it is amazing.

Coolant, just generic green stuff. If it is orange, throw it away!

 

This.

Everything else is just fluff.

 

Shell Rotella T6 is available in 0W40. Should be available at Walmart.
Valvoline will also have an equivalent formulation. Both are HDEO
with primary API "Cx" designation for diesel engines and secondary
"Sx" designation for spark engines.

You might like the latest Castrol 5W50 "classic car" formulation.

All of the above are not too exotic, so generally not too expensive.

I have used both the Shell and Castrol in the V8 seen in my sig.

Both spin well at well below freezing and I have every confidence
in both for extended high speed cruising. Never a top up between
oil changes at 6K miles.

 

I just remember in my 77 MGB putting synthetic in it (5w30 maybe??) and it spun the number 3 rod bearing....... And I also knew that the motor required a heavier weight oil but it's also a 1.8 liter inline 4 banger so.... As my Harley requires 20w50 as well.


I will do some oil shopping this weekend. I don't plan on running the car in the winter time so.... sounds like 20w50 is what I need then?

 

I wouldn't assume that putting synthetic oil in your MGB has anything to do with the spun bearing.

Follow the owner's manual for viscosity information combined with the advice above.

 

I use Mobil 1 0W40 in mine and the engine is quiet and runs silky smooth. I used 20W50 Castrol prior to Mobil 1 and the engine was not as smooth or quiet. The engine oil pressure stayed the same and so far no leaks... LOL.