Thanks Mag 454. I use amsoil in my '72 Buick GS. 20w50. Works great. I will give the 5w-30 a go in my KX8.

 

Thank you Aode, I stopped turning a wrench as a profession 40 years ago. Still play a bit today. Frim believer of synthetic. Your logic on the 5w-30 makes sense. Being old school the 5w part scares me... As does the 0w-30 on my new Sierra 6.2. Rich

 

Hi Chuck, I started using Synthetic in late 80's with my first 4 cam engine. Wife's Chev Lumina Z-34. Lots of things going on in multi cam engine. I noticed after oil changes the oil smelled burnt and dark. ( used top quality oils at time). Swithch to synthetic, clean oil for over 3k miles, lowered the coolant temp by almost 5 degrees. That z, 150k miles before sold, next 3.4 - 4 cam 238 mile before sold. 04 Pontiac GP Supercharged 160k, 06 GP supercharged my wife still drives at 150k going strong. The little extra $$ for full synthetic is worth to me. Thanks for you for your replay. Happy motoring Rich

 

Thank you ode 06. I agree 100%. I stopped turning a wrench as a profession a long x ago, however still around the dealer shops. Oil changes often with good oil is an inexpensive investment in my machines long after the warranty expires. Clogged arteries in your engine is not much different as clogged arteries in your body with the junk food we eat. Have not looked at the top guides yet on my 99 xk8 yet. Thank you for the tip on Lucas. Have had people in the past give same comment. guess it is time I start to listen.. Thank you again, Rich

 

I ma thinkin if u have enough file in the oil where as the mag makes a diff, the party is soon over. Thanks for the insurance idea however. I have had people tell me to place 2 aside the intake which improves fuel mileage??

 

Nice car ... is it a 455?

I love RWD Buicks. The XKR I bought last month is essentially the replacement for the the 64 Skylark convertible I had to sell when money was tight 3 years ago.

 

According to GULF advisor my XK8 should run on Gulf Formula G 5w/40 fully synthetic or Gulf Tec Plus 10w40 semi syntethic.

Gulf advise to change every 16.000 km (10k miles) or every 12 months. (Whatever comes first) BUT, under difficult conditions - change every 6 months.

 

Hi Auburn2, na, mine is a '72 Convertible with a 350 4bbl. Missed a black Stage I by / / this much back in '72. Did buy mine new. Took it to my 40th class reunion. What a hoot. Rich

 

I read somewhere modern oils don’t have the zinc needed to protect internal parts on this engine type. Any experience with zinc additives?

 

I think zinc (ZDDP) can poison the catalyst.

 

if you are referring to an XK- e type, yes, If you have a true vintage car, then elevated levels of zinc & phosphorus are desirable. But modern cars such as the X-100 series do just fine with modern, and hopefully synthetic, oils.

as mentioned, above, catalytic converters do not favorably tolerate boosted levels of zddp.

PS: re oil change intervals, the best way to determine the correct mileage for an oil and filter change is to have an oil analysis done by a reputable laboratory such as Blackstone. Price is very reasonable and not only indicates the proper oil change interval, but also gives you vital information re the health of the engine and rate of engine wear.


Z

 

Best oil advice:
Oil in sump = good
No oil in sump = bad



PS: I use Mobil One full syn 0-w40.

 

I'm using Rotella T4 15-40 non synthetic. The T4 still has some ZDDP ,though it's been reduced in the newer formulation, so that's good for flat tappet motors.. I change my oil every 3000 miles or less as I change it once a year and that's all the miles I put on in a year. I don't drive it during the winter so the heavier viscosity is not an issue. T4 also has additives that reduce oxidation. Oxidation leads to sludge deposits and more importantly, for my NIKASIL bore engine, increases the oils acidity.

 

i use it too. The temperatures in Oklahoma are extreme enough to warrant the departure from 5w-30. I also have the oil tested after each oil change by Blackstone labs. Aside from wanting to know if my additives package is still there, I like knowing the indicators of engine wear such as the ppm levels of iron.

Z

 

What would you use the wear information for? If I, for example, had an untreatable disease I am not sure I would wish to find out. Same with my car!

 

Iron or aluminum in the oil above normal levels would indicate accelerated cylinder or piston wear. Very treatable with new parts and or re-sleeved cylinders, or even a donor engine if that’s more financially viable . Likewise for main or rod bearing material. On most engine anything can be fixed or replaced before a catastrophic event takes place. But the main reason I like to have the oil tested is to know if the oils additives are still there, or have they been depleted by use.

on a personal level, if I had an untreatable ailment, I’d want to know. There might be a few things I’d like to see or do if my estimated life span was measured in weeks instead of in years. That said, regardless of my time left on earth, I try not to put anything enjoyable off, like driving the XKR,

I couldn’t let the car sit all winter for fear of a rust spot. I drive mine 365 says a year and wash the undercarriage off thoroughly after driving in ice or snow. Been doing that for every vehicle I’ve owned since 1967 and never have had a rust issue yet. I learned how to keep a car from rusting when I lived on the beach, where rust is a real issue. A little preventative care goes a long way,

Z

 

Thanks, Zray, a thoughtful and useful answer.