* Reliability between the two engines?
* Power vs gas mileage?
* Other?
Thanks!

 

I have the 3.0 in my S-Type and the 4.2 in my wife's XK8, so we're talking about two very different cars here. Still, I would say that given the proper care both engines are equally reliable. The S-Type is approaching 84,000 miles while the XK8 is approaching 81,000 miles. The only engine issues I've had to deal with involved the well-known requirement of having to replace the two factory IMT O-rings on the 3.0 due to misfires. Once I did this in March 2010, zero engine issues since....

The 3.0 easily achieves 33 to 34 mpg during my wife's long solo trips to Tampa and back to visit her mother. The 4.2 gets 27 to 28 mpg on that same trip. Of course, the 4.2 is more fun when you want it to be....

The 3.0 has always been happy with unleaded regular. The 4.2 does not like unleaded regular and will not perform optimally unless it is fed unleaded premium....

Decent oil and filters combined with sufficient change intervals (I do it at 6,000 miles) will keep both engines equally reliable....

 

Probably a better question is what year should you purchase?

Always try to get the 2003 and up models. The car looks the same but it is very much improved in nearly every way.

I think the 6 vs 8 question is more about power and fuel than reliability.
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I had a 2005 S-Type V6 that was dead-nuts reliable. As Jon noted, it's fairly good on highway gas mileage. I could get about 32-24 mpg at 75 mph. Interestingly enough the 2006 XJ I bought recently also gets about the same gas mileage, but due to the V8 it has a lot more torque.

Looking back, I would probably have gone with the V8, but at the time I was still spooked about the V8's problems with the cam chain tensioners, nikasel and water pumps. I chose the V6 because it was fairly well developed and I didn't read about any engine issues at the time (2009).

 

If getting a V8 I'd get the 4.2, then no nikasil or tensioner problems.

(well, I got the R)

 

Speaking of post facelift cars, the two engines are pretty much equally reliable and durable. The difference in fuel consumption is negligible.

 

The olde saying holds true: "There is no substitute for cubic inches".

Go with the V8 the car will be much more refined.
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You dreamed of a big star
he played a mean guitar
He loved to drive his Jaguar...

So welcome to the machine

 

I haven't lived with the V8 but Jon's comment seem consistent with other's experience - V8 is more higher strung and need premium gas. My V6 is happy to use regular(87 AKI) in US and return 30MPG on highway driving. This is with upgraded wheels and tires to 245/45-18.

 

Without rehashing a popular but controversial subject too deeply- both engine variants require 91 AKI fuel according to Jag. Similarly, both variants have been operated on 87 fuel without apparent issue.

 

There is no substitute for cubic inches.... unless it is supercharged cubic inches!!!

 

Hmm...

 

What Hmm?

It's a completely different car with who knows what ignition/control logic so most likely apples and oranges. Do you have experience with either the 6 cylinder or 8 cylinder NA S-types that might be relevant?

 

I have read this with interest and am in the same situation.

I find the 3.0's performance acceptable and much prefer the wood patterns and seat piping that seems to be more common in them.

The problem is just knowing there is a V-8 and a supercharged one no less available makes it hard to compromise away from an R.

Six months into the hunt for the right car and I am vacillating maybe a bit less but still walking......

 

Check the thread title and the OP's original question, and stop trying to pick a fight.

 

Robin- the thread title is" S Type 6 cyl. vs 8 cyl. Pros and cons?"


Jon89's reference to the 4.2 engine is with reference to his XK8, not an S-type, so is of limited value in answering the OP's specific question.

Have a nice day.

 

You will notice that the OP thanked Jon89 for his post of "limited value". His Victory XK8 has a 4.2 supercharged engine that can't be that different from the STR. Too bad you didn't address your disparaging remark to Jon89 at the time.

Jaguar specifies 91 AKI as the minimum to avoid damage to the S-type engine, not the maximum. What is it that you know about the S-type engine that Jaguar does not?

I consider it a disservice to forum members who ask for advice to suggest that 87 AKI Regular is OK for Jaguar V8 engines. Unless you have Jaguar's blessing on that opinion, or you drive like Miss Daisy all year round.

 

Point of clarification here - our XK8 has the normally-aspirated 4.2. If it were supercharged, it would be an XKR. Regardless, we know that my wife's XK8 requires unleaded premium for optimum performance. In nearly two-and-a-half years of ownership, I've tried multiple tanks of unleaded regular. The car is simply not as peppy when running regular gas and my wife can always tell when I've filled her car up with regular and is never happy about it....

Now, on with the battle....

 

I have no reason to doubt your experience with either of your cars and thank you in particular for the input on the 6 cylinder S-type. This partially answers the OP's question.

I contributed my experience in using 87 octane fuel with my 4.2 NA S-Type, which matches your experience with the 3.0. This helps answer another part of the OP's question.

Then we have another contributor who owns neither and has no direct experience but is once again casting doubt and attempting to cause confusion.

How does this help the OP?

 

Only the OP can answer your question. He may have gleaned whatever information he was looking for and moved on by now....

 

Hi Jon,

I'm pretty sure my XJ has the same engine as your wife's XK. I have been using the mid-grade so far and the car seems OK with it. I haven't tried the super premium yet though. I did notice that my S-Type ran a little better with the Sunoco super premium and I ran it when the prices were down. I'll have to try a tankful of the super premium on my next fill up to see what differences (if any) there are. The XJ has a huge gas tank so it may be awhile.